[11.x] Refactor and add remaining test cases for the DatabaseFailedJobProviderTest class

[kevinb1989]

This PR is very similar to #53408, I would like to refactor and add test cases for remaining methods of the Illuminate\Queue\Failed\DatabaseFailedJobProvider class.

This includes:

• Extract the following code snippets to new methods:
  • creating a database instance
  • creating a provider instance
  • inserting records to the failed_jobs table
• Create test cases for the following methods:
  • ids
  • all
  • find
  • forget
  • prune