The warning for a patch not submitted should be triggered only for agents that are supposed to submit patches

Regressed by https://github.com/mozilla/bugbug/issues/6683

The warning will now trigger for any agent, even those who don’t use the Phabricator submit tool. This is more of a false alarm and doesn’t help in detecting issues.

Related Sentry issue: [HACKBOT-API-H](https://mozilla.sentry.io/issues/7703524637/?referrer=github_integration)