Fix mistakes in time subpackage docstrings / arguments - #20216

Description

This pull request used AI to audit the astropy/time subpackage for discrepancies in function arguments and docstrings.

1. TimeBase._apply (stale docstring)
   format and cls were promoted to explicit keyword-only params in the code, but the docstring still described format as something arriving via kwargs and cls was undocumented entirely. Documented both properly and dropped the stale sentence.

2. TimeDelta.__new__ (dead parameter)
   location=None was in the signature but not the class docstring. Here the docstring was right and the signature was wrong: location is copy-paste residue from Time.__new__ (where it's real). TimeDelta.__init__ never accepted it, so TimeDelta(..., location=...) always raised TypeError — the parameter was unreachable. Removing this parameter does not change the outcome of providing location which would still be a TypeError.

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