Use RetryError for DeleteBranchWorker

What does this MR do and why?

• Contributes to #387018 (closed)
• Sentry error: https://sentry.gitlab.net/gitlab/gitlabcom/issues/4075191/?referrer=gitlab_plugin
• Follow-up for: !103842 (merged)

Problem

#track_and_raise_exception raises a standard error that gets reported to Sentry.

Solution

• Add log_and_raise_exception method to log error in Kibana and re-raise the exception
• Use Gitlab::SidekiqMiddleware::RetryError exception to avoid noise in Sentry
• Add documentation to cover RetryError usage

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.