[EngSys][ServiceBus/Tables] Remove workaround in preparers.py after fixing cosmos non-recording tests.

[KieranBrantnerMagee]

For the hotfix here

This fix should be deprecated and the underlying problem addressed. It was initially constructed to handle tests that were marked live but did not have a recording/did not generate HTTP traffic, but if used in cached mode, this would cause problems with how the in_recording variable is set. (it sets a random name which is then preserved in the cache)

In conversation with @lmazuel there is a more appropriate angle to fix this: Tests that do not generate recordings simply should not be AzureTestCases. Either the work to set up the resource should be in the test, not a preparer, (if you actually wanted a live resource) or it should be mocked and unit-testable.

One of these fixes should be applied to the cosmos tests in question, and the workaround clause should be yanked.

[ghost]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @southpolesteve, @zfoster