Ignore .cxx/ directories (#9268)

Android builds now create .cxx directories in some cases; this has been added to the app template's ignore file, so should be ignored here as well. As is generally the case for this repo, we ignore it at the root level instead of updating every package.

Author: stuartmorgan-g

.gitignore

@@ -53,6 +53,7 @@ GeneratedPluginRegistrant.*
 .gradle/
 gradlew
 gradlew.bat
+.cxx/
 
 .project
 .classpath

script/tool/lib/src/drive_examples_command.dart

@@ -71,7 +71,13 @@ class DriveExamplesCommand extends PackageLoopingCommand {
 
   @override
   bool shouldIgnoreFile(String path) {
-    return isRepoLevelNonCodeImpactingFile(path) || isPackageSupportFile(path);
+    return isRepoLevelNonCodeImpactingFile(path) ||
+        isPackageSupportFile(path) ||
+        // This isn't part of isRepoLevelNonCodeImpactingFile since there could
+        // potentially be code-based commands that it could affect, but it
+        // should not affect integration tests, and they are the most expensive
+        // and flaky tests.
+        path == '.gitignore';
   }
 
   @override

script/tool/test/drive_examples_command_test.dart

@@ -1763,6 +1763,7 @@ packages/package_a/$file
           FakeProcessInfo(MockProcess(stdout: '''
 README.md
 CODEOWNERS
+.gitignore
 packages/package_a/CHANGELOG.md
 ''')),
         ];