Opt out bin/internal/engine.version from most presubmits. (#4715)

Closes flutter/flutter#169139.

Author: matanlurey

app_dart/lib/src/service/scheduler/files_changed_optimization.dart

@@ -66,25 +66,33 @@ final class FilesChangedOptimizer {
         log.warn('$refusePrefix: $reason');
         return FilesChangedOptimization.none;
       case SuccessfulFilesChanged(:final filesChanged):
-        var markdownOnly = true;
+        var noSourceImpact = true;
         for (final file in filesChanged) {
           if (file == 'DEPS' || file.startsWith('engine/')) {
             log.info(
               '$refusePrefix: Engine sources changed.\n${filesChanged.join('\n')}',
             );
             return FilesChangedOptimization.none;
           }
-          if (markdownOnly && p.posix.extension(file) != '.md') {
-            markdownOnly = false;
+          if (noSourceImpact &&
+              p.posix.extension(file) != '.md' &&
+              file != _binInternalEngineVersion) {
+            noSourceImpact = false;
           }
         }
-        if (!markdownOnly) {
+        if (!noSourceImpact) {
           return FilesChangedOptimization.skipPresubmitEngine;
         } else {
           return FilesChangedOptimization.skipPresubmitAllExceptFlutterAnalyze;
         }
     }
   }
+
+  static final _binInternalEngineVersion = p.posix.join(
+    'bin',
+    'internal',
+    'engine.version',
+  );
 }
 
 /// Given a [FilesChanged], a determined safe optimization that can be made.

app_dart/test/service/scheduler/files_changed_optimization_test.dart

@@ -152,6 +152,26 @@ void main() {
     );
   });
 
+  test('include bin/internal/engine.version as ignored', () async {
+    final optimizer = FilesChangedOptimizer(
+      getFilesChanged: filesChanged([
+        'README.md',
+        'CONTRIBUTING.md',
+        'bin/internal/engine.version',
+        'packages/flutter_tools/lib/src/engine/NOT_THE_ENGINE.md',
+      ]),
+      ciYamlFetcher: ciYamlFetcher(slug: Config.flutterSlug),
+      config: config(maxFilesChangedForSkippingEnginePhase: 100),
+    );
+
+    await expectLater(
+      optimizer.checkPullRequest(
+        generatePullRequest(repo: 'flutter', changedFilesCount: 4, number: 123),
+      ),
+      completion(FilesChangedOptimization.skipPresubmitAllExceptFlutterAnalyze),
+    );
+  });
+
   test('only non-engine files', () async {
     final optimizer = FilesChangedOptimizer(
       getFilesChanged: filesChanged(['packages/flutter/lib/flutter.dart']),