gh-94808: Cover LOAD_GLOBAL for custom dict subtypes

[sobolevn]

I've covered several missing conditions in TARGET(LOAD_GLOBAL):

• The one where custom globals() dict subtype raises non KeyError:

  cpython/Python/ceval.c

  Lines 2445 to 2447 in 53a54b7

  	if (!_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
  	goto error;
  	}

• Similar case where __builtins__ dict subtype raises non KeyError:

  cpython/Python/ceval.c

  Line 2458 in 53a54b7

  goto error;

• Regular NameError in a custom __builtins__ dict subtype:

  cpython/Python/ceval.c

  Lines 2453 to 2457 in 53a54b7

  	if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
  	format_exc_check_arg(
  	tstate, PyExc_NameError,
  	NAME_ERROR_MSG, name);
  	}

• Issue: Metabug: Improving C-level coverage #94808

[mdboom]

LGTM. Thanks for the contribution.

[iritkatriel]

This should be defined just before the test that uses it (below). Ideally this function would be broken up - it's testing a lot of things.

[sobolevn]

Done! Thanks!

[miss-islington]

Thanks @sobolevn for the PR, and @iritkatriel for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10, 3.11.
🐍🍒⛏🤖

[miss-islington]

Sorry, @sobolevn and @iritkatriel, I could not cleanly backport this to 3.10 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 044bcc1771fe7e2f8eba21793a72ba15e75e6715 3.10

[bedevere-bot]

GH-99091 is a backport of this pull request to the 3.11 branch.