Move integration_test dependencies to non-dev_dependencies. (#160380)

First part of https://github.com/flutter/flutter/issues/160379.

This should be a NOP, because without the
`explicit-package-dependencies` feature flag, all dependencies
(including dev_dependencies) are considered, for the purposes of
plugins, non-dev dependencies.

This change prepares for flipping that flag, so when the flip occurs, it
is _also_ a NOP for these tests.

dev/benchmarks/complex_layout/pubspec.yaml

@@ -10,6 +10,14 @@ dependencies:
   flutter_driver:
     sdk: flutter
 
+  # TODO(matanlurey): Move to dev_dependencies (https://github.com/flutter/flutter/issues/160379).
+  #
+  # As part of https://github.com/flutter/flutter/issues/160257, integration_test as a dev_dependency
+  # will be removed in release mode, but some of our tests and CI tasks are written in a way where they
+  # expect integration_test to never be removed.
+  integration_test:
+    sdk: flutter
+
   # To change the version of the gallery assets, edit
   #   //packages/flutter_tools/lib/src/commands/update_packages.dart
   # and run
@@ -40,8 +48,6 @@ dev_dependencies:
   flutter_test:
     sdk: flutter
   test: 1.25.12
-  integration_test:
-    sdk: flutter
 
   _fe_analyzer_shared: 76.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   analyzer: 6.11.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"

dev/benchmarks/macrobenchmarks/pubspec.yaml

@@ -47,6 +47,12 @@ dependencies:
 
 dev_dependencies:
   test: 1.25.12
+
+  # TODO(matanlurey): Move to dev_dependencies (https://github.com/flutter/flutter/issues/160379).
+  #
+  # As part of https://github.com/flutter/flutter/issues/160257, integration_test as a dev_dependency
+  # will be removed in release mode, but some of our tests and CI tasks are written in a way where they
+  # expect integration_test to never be removed.
   integration_test:
     sdk: flutter