Fix intermittent validator_exit test failure

[HaoranYi]

Problem

Due to shared resources between validator_exit and validator_parallel_exit, when they are executed in parallel by the rust test executor, these tests hangs.

Summary of Changes

Use one test function to run both tests.

Fixes #

[codecov]

Codecov Report

Merging #23594 (80db282) into master (2da4e3e) will decrease coverage by 0.1%.
The diff coverage is 75.6%.

❗ Current head 80db282 differs from pull request most recent head 79524ba. Consider uploading reports for the commit 79524ba to get more accurate results

@@            Coverage Diff            @@
##           master   #23594     +/-   ##
=========================================
- Coverage    81.8%    81.6%   -0.2%     
=========================================
  Files         581      583      +2     
  Lines      158312   159173    +861     
=========================================
+ Hits       129518   130044    +526     
- Misses      28794    29129    +335     

[t-nelson]

Can you remove (or move to a separate commit) the code shuffle in 9f56e89? It hides the logical changes

[HaoranYi]

Can you remove (or move to a separate commit) the code shuffle in 9f56e89? It hides the logical changes

Yes. good idea.

[t-nelson]

lgtm. just a curiosity to entertain

[jstarry]

Is it true that these two tests actually share resources? From my understanding they shouldn't be. I think we should revert this change in favor of the real fix (#24007 + #24036)

[HaoranYi]

@jstarry Sure. Good point. I will create another pull request to revert this change. Thanks!