Improve EnforceDistribution testings.

[wiedld]

Is your feature request related to a problem or challenge?

We have two primary goals: (1) ensure the test coverage includes use cases we encounter in prod, and (2) make the existing test suite easier to understand.

Describe the solution you'd like

For the existing tests:

• use an easier to read formatting of plans:
  • Minor: Add indentation to EnforceDistribution test plans. #15007
• convert the existing macro with up to 8 vargs, into something easier to reason about (e.g. builder pattern, etc):
  • Refactor test suite in EnforceDistribution, to use standard test config. #15010
• enable running any series of optimizer runs over the plans, using the new testing framework:
  • Refactor EnforceDistribution test cases to demonstrate dependencies across optimizer runs. #15074
• move existing tests (in that file) into the new testing framework (now possible with custom list of optimizer runs)

For the improved test coverage:

• add idempotency test cases
• have test cases not using not using batch_size=1 (existing test cases hardcode it to =1 to force roundrobin repartitioning).
• have test cases include data source with statistics, otherwise we always hit this branch point, which often forces roundrobin repartitiong.
• have test cases without join key reordering, otherwise we never hit this branch.
• TBD: based on codecov reports

Describe alternatives you've considered

N/A

Additional context

No response

[wiedld]

take

[wiedld]

@berkaysynnada and @alamb -- issue we discussed this morning.
I'll add more tasks to the description if needed; this is the starting set.

[berkaysynnada]

I couldn't get this today, sorry. That will be my priority tomorrow