Closes #19477: remove outdated documentation of tp_print type object slot.
Issue #22290: Fix error handling in the _posixsubprocess module.

* Don't call the garbage collector with an exception set: it causes an
  assertion to fail in debug mode.
* Enhance also error handling if allocating an array for the executable list
  failed.
* Add an unit test for 4 different errors in the _posixsubprocess module.
Issue #22390: Remove files created by tests
cleanup test_posix