Make runner handling more resilient

What does this MR do?

Retry getting the runners token if it's not available initially, which can happen if the runner is to be used in a group that was just created by the API.

Ensure the docker runner container is stopped even if there's a problem removing it from the project.

Closes #118453 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] 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