Do not use seeded_test fixture in exported BaseTestDistributionRandom

[ricardoV94]

This caused pymc-experimental to fail as the test is used there but there is no access to the fixture.
The fixture was added after the changes in #6799
I don't think we need it?

CC @aerubanov

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📚 Documentation preview 📚: https://pymc--6848.org.readthedocs.build/en/6848/

[codecov]

Codecov Report

Merging #6848 (0f713e5) into main (ccad4c8) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6848      +/-   ##
==========================================
- Coverage   92.05%   92.03%   -0.02%     
==========================================
  Files          96       96              
  Lines       16369    16369              
==========================================
- Hits        15068    15065       -3     
- Misses       1301     1304       +3     

Files Changed	Coverage Δ
pymc/testing.py	91.46% <100.00%> (ø)

... and 1 file with indirect coverage changes

[aerubanov]

@ricardoV94 Yeah, looks like seeded_test fixture is actually is not needed here.

[jessegrabowski]

LGTM. The tests even seem like they were written to be like this in the first place (judging from the partial functions that pass in the random state)