REF: simplify extension reduction tests

[jbrockmendel]

• closes API: extension tests BaseNoReduceTests/BaseBooleanReduceTests is confusing #44742 (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

Will clean up the pyarrow tests usage in a follow-up.

Didn't remove the no-longer-used test classes since downstream projects might be using them. Are we OK just ripping those out or does that require a deprecation cycle?

[mroeschke]

Are we OK just ripping those out or does that require a deprecation cycle?

Probably should deprecate them since we advertise users to test with them, but since it's not extremely public maybe we can do a 3.0 change?

[jbrockmendel]

Probably should deprecate them since we advertise users to test with them, but since it's not extremely public maybe we can do a 3.0 change?

Works for me

[jbrockmendel]

Probably should deprecate them since we advertise users to test with them, but since it's not extremely public maybe we can do a 3.0 change?

Just checking: you mean OK to move forward with this PR as is then remove the old classes in 3.0?

[mroeschke]

you mean OK to move forward with this PR as is then remove the old classes in 3.0?

Yeah I think deprecating tests is sticky business and probably just worth noting in 3.0 to use a different test class

[mroeschke]

Thanks @jbrockmendel