Refactor cluster application services

What does this MR do?

• Refactor services to be more generic so that we can remove the duplication in the next step.
• Stop rescuing errors from app.make_scheduled!

Any errors arising from app.make_scheduled! is un-expected and we should not hide the error.

Also we currently have to have #make_update_errored just solely to be able to transition from scheduled to update_errored in the case of a update, vs #make_errored in the case of a install. It will be great to be able to remove this distinction.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Performance 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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team