feat(discover): Split Discover Dataset task

[shruthilayaj]

Task that will split Discover saved queries This PR just introduces the task (doesn't actually run it)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 78.84615% with 55 lines in your changes missing coverage. Please review.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/sentry/discover/dataset_split.py	84.00%	14 Missing and 14 partials :warning:
src/sentry/tasks/split_discover_query_dataset.py	67.46%	21 Missing and 6 partials :warning:

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #76201       +/-   ##
===========================================
+ Coverage   57.31%   78.18%   +20.86%     
===========================================
  Files        6898     6906        +8     
  Lines      306775   307046      +271     
  Branches    50296    50324       +28     
===========================================
+ Hits       175829   240059    +64230     
+ Misses     126160    60577    -65583     
- Partials     4786     6410     +1624     

[shruthilayaj]

One thing to consider would be to unit-test the functions in dataset_split, but they're e2e tested which is fine

I added some unit tests for the logic that splits datasets without querying snuba! https://github.com/getsentry/sentry/pull/76201/commits/38240918891fd3fbf09fb9b24e57f0bfc9849484#diff-1f53d05795f5e5a6afb8672dc304c7a1ca0403f167e76d62d659cb00e09b5e8dR544