Update xcode to 14c18 (flutter/engine#41370)

With https://flutter-review.googlesource.com/c/recipes/+/42160, we are
ready to make all tests consistent with xcode 14c18.

Fixes https://github.com/flutter/flutter/issues/125216

engine/src/flutter/.ci.yaml

@@ -54,7 +54,7 @@ platform_properties:
       device_type: none
       cpu: x86
       os: Mac-12
-      xcode: 14a5294e # xcode 14.0 beta 5
+      xcode: 14c18
     dimensions:
       mac_model: "Macmini8,1|Macmini9,1"
   windows:
@@ -360,7 +360,7 @@ targets:
           {"dependency": "goldctl", "version": "git_revision:3a77d0b12c697a840ca0c7705208e8622dc94603"}
         ]
       $flutter/osx_sdk : >-
-        { "sdk_version": "14a5294e" }
+        { "sdk_version": "14c18" }
 
   - name: Linux mac_unopt
     recipe: engine_v2/engine_v2
@@ -439,7 +439,7 @@ targets:
       release_build: "true"
       config_name: mac_ios_engine
       $flutter/osx_sdk : >-
-        { "sdk_version": "14a5294e" }
+        { "sdk_version": "14c18" }
       dependencies: >-
         [
           {"dependency": "jazzy", "version": "0.14.1"}

engine/src/flutter/ci/builders/README.md

@@ -70,7 +70,7 @@ Ci\_yaml file is the glue sticking all the components together. A new build will
     properties:
       config_name: mac_android_aot_engine
       $flutter/osx_sdk : >-
-        { "sdk_version": "14a5294e" }
+        { "sdk_version": "14c18" }
 
 ```
 

engine/src/flutter/ci/builders/mac_unopt.json

@@ -32,7 +32,7 @@
             },
             "properties": {
                 "$flutter/osx_sdk": {
-                    "sdk_version": "14a5294e"
+                    "sdk_version": "14c18"
                 }
             },
             "tests": [
@@ -63,9 +63,10 @@
             "properties": {
                 "$flutter/osx_sdk": {
                     "runtime_versions": [
+                        "ios-16-2_14c18",
                         "ios-16-0_14a5294e"
                     ],
-                    "sdk_version": "14a5294e"
+                    "sdk_version": "14c18"
                 }
             },
             "drone_dimensions": [
@@ -153,7 +154,7 @@
             },
             "properties": {
                 "$flutter/osx_sdk": {
-                    "sdk_version": "14a5294e"
+                    "sdk_version": "14c18"
                 }
             },
             "tests": []
@@ -170,8 +171,11 @@
             ],
             "properties": {
                 "$flutter/osx_sdk": {
-                    "runtime_versions": [ "ios-16-0_14a5294e" ],
-                    "sdk_version": "14a5294e"
+                    "runtime_versions": [
+                        "ios-16-2_14c18",
+                        "ios-16-0_14a5294e"
+                    ],
+                    "sdk_version": "14c18"
                 }
             },
             "drone_dimensions": [