docs: remove falsely advertised parameters from sc.pl.scatter

[flying-sheep]

• Closes TypeError: scatter() got an unexpected keyword argument 'colorbar_loc' #3893
• Tests included or not required because:

• Release notes not necessary because:

looks like all the hairy manual padding stuff would not play well with actually supporting it, so away it goes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.82%. Comparing base (10fe134) to head (1b1d614).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3894   +/-   ##
=======================================
  Coverage   76.82%   76.82%           
=======================================
  Files         116      116           
  Lines       12398    12398           
=======================================
  Hits         9525     9525           
  Misses       2873     2873           

Flag	Coverage Δ
hatch-test.pre	76.82% <100.00%> (ø)

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Files with missing lines	Coverage Δ
src/scanpy/plotting/_anndata.py	85.58% <100.00%> (ø)
src/scanpy/plotting/_docs.py	100.00% <ø> (ø)
src/scanpy/plotting/_tools/scatterplots.py	83.13% <ø> (ø)
src/scanpy/plotting/_utils.py	77.57% <ø> (ø)