Remove the old HaTS implementation on API docs (#28683)

dev/docs/survey.html

-<script async="" defer=""
-  src="//www.google.com/insights/consumersurveys/async_survey?site=i2bdmo2dzky7fqws25nicgx5f4">
-</script>
-<script async="" defer="" src="../assets/api_survey.js"></script>

dev/tools/dartdoc.dart

@@ -136,7 +136,6 @@ Future<void> main(List<String> arguments) async {
     '--inject-html',
     '--header', 'styles.html',
     '--header', 'analytics.html',
-    '--header', 'survey.html',
     '--header', 'snippets.html',
     '--header', 'opensearch.html',
     '--footer-text', 'lib/footer.html',