Use @gitlab/favicon-overlay instead of common_utils

What does this MR do?

As part of #287678 (closed), we've moved our favicon overlay utilities over to their own package (many thanks to @winniehell!). This package has significantly better test coverage than our current one and will also free up some CI resources since it's tests are decoupled from our pipeline.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• [ ] Changelog entry There shouldn't be any user-facing change here
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [ ] Informed Infrastructure department of a default or new setting change, if applicable per [definition of done](https://docs.gitlab.com/ee/development/contributing/merge_request_workflow.html#definition-of-done