refactor(runloop): use utils.get_updated_monotonic_ms()

[chronolaw]

Summary

In PR #11627 we introduced a new function get_updated_monotonic_ms() in tools.utils,
so we can replace the same implementation in runloop.handler.

Checklist

• The Pull Request has tests
• A changelog file has been added to CHANGELOG/unreleased/kong or adding skip-changelog label on PR if unnecessary. README.md
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Full changelog

• [Implement ...]

Issue reference

Fix #[issue number]