Use fixture for ray clusters in tests

[tgaddair]

[github-actions[bot]]

Unit Test Results

       4 files   -     2         4 suites   - 2   1h 24m 36s :stopwatch: - 58m 31s 2 911 tests ±    0  2 863 :heavy_check_mark:  -     3  45 :zzz: ±  0  1 :x: +1  2 :fire: +2  8 483 runs   - 250  8 383 :heavy_check_mark:  - 211  97 :zzz:  - 42  1 :x: +1  2 :fire: +2 

For more details on these failures and errors, see this check.

Results for commit 149b6264. ± Comparison against base commit 97aa9f1f.

:recycle: This comment has been updated with latest results.

[arnavgarg1]

Should we rebase + resolve conflicts and merge this into master? Feels like a very useful change.