Remove code around Clusters::Applications::WaitForUninstallAppWorker

What does this MR do and why?

Remove clusters_applications_* code (#366573 - closed) relates to removing clusters_applications_* code, as it is no longer in use and the UI related to it has been removed. We want to break that issue down into several smaller MRs. This MR beings removing code around Clusters::Applications::WaitForUninstallAppWorker

What this MR does

• Noop Clusters::Applications::WaitForUninstallAppWorker#perform.
• Delete Clusters::Applications::CheckUninstallProgressService which is only invoked from Clusters::Applications::WaitForUninstallAppWorker.
• Delete unit specs for deleted classes.
• Address any other failing specs impacted.

Numbered steps to set up and validate the change are strongly suggested.

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.