Revert "Add verbose logging for customer testing shard (#154356)"

This reverts commit 1c6defcbffc326c6fe3e99d8095cf0069090116a.

dev/customer_testing/run_tests.dart

diff --git a/dev/customer_testing/run_tests.dart b/dev/customer_testing/run_tests.dart
index 95eda2d..276402b 100644
--- a/dev/customer_testing/run_tests.dart
+++ b/dev/customer_testing/run_tests.dart
@@ -129,9 +129,7 @@
   return runTests(
     repeat: repeat,
     skipOnFetchFailure: skipOnFetchFailure,
-    // TODO(Piinks): Restore after resolving https://github.com/flutter/flutter/issues/154251
-    // Needed to see time stamps of individual test runs and identify long running test.
-    verbose: true,
+    verbose: verbose,
     numberShards: numberShards,
     shardIndex: shardIndex,
     files: files,