Log when a pipeline creation limit is hit

What does this MR do?

Related issue: #32823 (closed)

Add logging when a pipeline is dropped because of an exceeded limit.

I went with Gitlab::Sentry logging because we have a MR that will allow us to do Gitlab::Sentry.log_exception(e) into a dedicated logger file that will be indexed in Kibana.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content