Simplify settings access

For Android >= 12, scrcpy executed "settings" commands (in a new
process) rather than using the ContentProvider directly, due to
permission issues [1].

However, these permission issues were resolved by introducing
FakeContext.getContentResolver() [2].

Therefore, remove the use of "settings" commands and use the
ContentProvider directly in all cases.

Refs [1] cc0902b13c87fc98b1ed90b0700cc53ac4d7ee3c
Refs [2] 91373d906b100349de959f49172d4605f66f64b2
Refs #6224 comment <https://github.com/Genymobile/scrcpy/issues/6224#issuecomment-3078418268>