Fix implementation of several RandomVariables in JAX backend

[ricardoV94]

Description

Spinoff from problems found in #691

Also closes #395

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks)
• If you are a pro: each commit corresponds to a relevant logical change

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):

[ricardoV94]

This was working fine, but not all branches were being tested so I added them

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.84%. Comparing base (db73461) to head (d697cd6).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #767      +/-   ##
==========================================
+ Coverage   80.83%   80.84%   +0.01%     
==========================================
  Files         162      162              
  Lines       46860    46877      +17     
  Branches    11465    11469       +4     
==========================================
+ Hits        37877    37896      +19     
- Misses       6732     6733       +1     
+ Partials     2251     2248       -3     

Files	Coverage Δ
pytensor/compile/mode.py	84.40% <ø> (ø)
pytensor/link/jax/dispatch/random.py	96.33% <100.00%> (+0.27%)	⬆️

... and 4 files with indirect coverage changes

[aseyboldt]

Looks good :-)