Decrease delay for RepositoryUpdateMirrorWorker

What does this MR do and why?

• Contributes to #364799 (closed)
• Follow-up for !90749 (merged)

The change is behind the disabled feature flag.

Problem

• QA tests started failing because Timeout errors.
• Delayed jobs started piling up

Solution

Decrease delay to resolve both problems.

Screenshots or screen recordings

See !90749 (merged)

How to set up and validate locally

See !90749 (merged)

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.