codegen error handling bugs

[iritkatriel]

I'm reviewing codegen and seeing some bugs in cleanup on errors, in particular scope enter/exit bugs.
Will use this issue to track them.

Linked PRs

• gh-156466: fix cleanup on error after Enter in codegen_enter_scope #156467
• gh-156466: fix cleanup on error in codegen_setup_annotations_scope #156473
• gh-156466: fix cleanup on error in codegen_leave_annotations_scope #156497
• [3.15] gh-156466: fix cleanup on error in codegen_setup_annotations_scope (#156473) #156498
• [3.14] gh-156466: fix cleanup on error in codegen_setup_annotations_scope (#156473) #156499