[newauth] Recommend creds-check in warning

Dissuade users from removing their .gitcookies manually.

Just to create a single UX path and prevent possible issues.

Bug: 408225524
Change-Id: Ief48806dccf759ead8d145424c854561e09d43ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6440131
Commit-Queue: Allen Li <ayatane@chromium.org>
Reviewed-by: Gavin Mak <gavinmak@google.com>

newauth.py

@@ -51,12 +51,11 @@ def _PrintGitcookiesWarning() -> None:
     if _warning_printed:
         return
     _warning_printed = True
-    sys.stderr.write(f'''
+    sys.stderr.write('''
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Warning !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 depot_tools will soon stop using the .gitcookies file for authentication.
 
-To silence this warning, please move or delete {os.path.expanduser('~/.gitcookies')},
-or you can run `git cl creds-check` which will help you fix this.
+To silence this warning, please run `git cl creds-check` which will help you fix this.
 
 If you encounter any issues, please report them using:
 https://issues.chromium.org/issues/new?component=1456702&template=2076315