[tool] Removes deprecated --web-renderer parameter. (#159314)

Removes the `--web-renderer` option.

Flutter tool users won't be able to select their web renderer.

In order to not drop test coverage, tests are still run with the HTML
Renderer, until its code is fully removed from the engine.

Part of https://github.com/flutter/flutter/issues/145954

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

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[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
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https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
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[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

dev/bots/suite_runners/run_web_tests.dart

@@ -105,7 +105,7 @@ class WebTestsSuite {
           testAppDirectory: path.join('packages', 'integration_test', 'example'),
           target: path.join('test_driver', 'failure.dart'),
           buildMode: buildMode,
-          renderer: 'canvaskit',
+          webRenderer: 'canvaskit',
           // This test intentionally fails and prints stack traces in the browser
           // logs. To avoid confusion, silence browser output.
           silenceBrowserOutput: true,
@@ -115,7 +115,7 @@ class WebTestsSuite {
           target: path.join('integration_test', 'example_test.dart'),
           driver: path.join('test_driver', 'integration_test.dart'),
           buildMode: buildMode,
-          renderer: 'canvaskit',
+          webRenderer: 'canvaskit',
           expectWriteResponseFile: true,
           expectResponseFileContent: 'null',
         ),
@@ -124,7 +124,7 @@ class WebTestsSuite {
           target: path.join('integration_test', 'extended_test.dart'),
           driver: path.join('test_driver', 'extended_integration_test.dart'),
           buildMode: buildMode,
-          renderer: 'canvaskit',
+          webRenderer: 'canvaskit',
           expectWriteResponseFile: true,
           expectResponseFileContent: '''
 {
@@ -177,7 +177,7 @@ class WebTestsSuite {
         testAppDirectory: path.join(flutterRoot, 'examples', 'hello_world'),
         target: 'test_driver/smoke_web_engine.dart',
         buildMode: 'profile',
-        renderer: 'auto',
+        webRenderer: 'auto',
       ),
       () => _runGalleryE2eWebTest('debug'),
       () => _runGalleryE2eWebTest('debug', canvasKit: true),
@@ -278,7 +278,7 @@ class WebTestsSuite {
     await _runFlutterDriverWebTest(
       target: path.join('test_driver', '$name.dart'),
       buildMode: buildMode,
-      renderer: renderer,
+      webRenderer: renderer,
       testAppDirectory: path.join(flutterRoot, 'dev', 'integration_tests', 'web_e2e_tests'),
     );
   }
@@ -286,7 +286,7 @@ class WebTestsSuite {
   Future<void> _runFlutterDriverWebTest({
     required String target,
     required String buildMode,
-    required String renderer,
+    required String webRenderer,
     required String testAppDirectory,
     String? driver,
     bool expectFailure = false,
@@ -318,7 +318,24 @@ class WebTestsSuite {
         '-d',
         'web-server',
         '--$buildMode',
-        '--web-renderer=$renderer',
+        // '--web-renderer=$webRenderer',
+        '--dart-define=FLUTTER_WEB_AUTO_DETECT=false',
+        if (webRenderer == 'skwasm') ...<String>[
+          // See: WebRendererMode.dartDefines[skwasm]
+          '--dart-define=FLUTTER_WEB_USE_SKIA=false',
+          '--dart-define=FLUTTER_WEB_USE_SKWASM=true',
+        ],
+        if (webRenderer == 'canvaskit') ...<String>[
+          // See: WebRendererMode.dartDefines[canvaskit]
+          '--dart-define=FLUTTER_WEB_USE_SKIA=true',
+          '--dart-define=FLUTTER_WEB_USE_SKWASM=false',
+        ],
+        if (webRenderer == 'html') ...<String>[
+          // See: WebRendererMode.dartDefines[html]
+          '--dart-define=FLUTTER_WEB_USE_SKIA=false',
+          '--dart-define=FLUTTER_WEB_USE_SKWASM=false',
+        ],
+
       ],
       expectNonZeroExit: expectFailure,
       workingDirectory: testAppDirectory,
@@ -695,7 +712,23 @@ class WebTestsSuite {
         '-v',
         '--platform=chrome',
         if (useWasm) '--wasm',
-        '--web-renderer=$webRenderer',
+        '--dart-define=FLUTTER_WEB_AUTO_DETECT=false',
+        // '--web-renderer=$webRenderer',
+        if (webRenderer == 'skwasm') ...<String>[
+          // See: WebRendererMode.dartDefines[skwasm]
+          '--dart-define=FLUTTER_WEB_USE_SKIA=false',
+          '--dart-define=FLUTTER_WEB_USE_SKWASM=true',
+        ],
+        if (webRenderer == 'canvaskit') ...<String>[
+          // See: WebRendererMode.dartDefines[canvaskit]
+          '--dart-define=FLUTTER_WEB_USE_SKIA=true',
+          '--dart-define=FLUTTER_WEB_USE_SKWASM=false',
+        ],
+        if (webRenderer == 'html') ...<String>[
+          // See: WebRendererMode.dartDefines[html]
+          '--dart-define=FLUTTER_WEB_USE_SKIA=false',
+          '--dart-define=FLUTTER_WEB_USE_SKWASM=false',
+        ],
         '--dart-define=DART_HHH_BOT=$runningInDartHHHBot',
         ...flutterTestArgs,
         ...tests,