Refactor pocket

[Brambor]

Summary

None

Purpose of change

While trying to understand the code, I found some things to improve.

Describe the solution

1. (1st commit) rename parameter is_pick_up_inv to ignore_non_container_pocket and document it.
   • I know renaming is bad, but the name was even worse. What does it mean? Do not count magazine as pocket in the pickup inventory #73107 which added the parameter has the answer.
2. (2nd commit) Make it a single, translatable sentence. If there is a language that uses periods differently, it can do so in this menu as well. It was not done before for historical reasons.
3. (3rd commit) Unimplemented parameter with no docs of what it does, used nowhere. This PR removes it.

Describe alternatives you've considered

1. Just document is_pick_up_inv instead of renaming it. The doc comment would confuse the programmer as to why the parameter has such a weird name.

Testing

1. Compiles.
2. Sentence is still right (has period at the end, there is no weird spacing):
   • 

Additional context

More refactoring is possible, but I plan to change the "Can be stored in" menu. Then the code will change too.

[Brambor]

I believe the test failure is unrelated https://github.com/CleverRaven/Cataclysm-DDA/actions/runs/12937209329/job/36084633496?pr=79305.

Restarting tests.