Remove dead code identified by static analysis

[duriantaco]

Hi! Just doing some cleanup..

Description

Remove unused functions, methods, and classes with zero callers, identified by Skylos

Removed:

• ListenBrainzPlugin.get_weekly_exploration, get_weekly_jams, get_last_weekly_exploration, get_last_weekly_jams: unused convenience wrappers in beetsplug/listenbrainz.py (never called anywhere in the codebase)
• FtInTitlePlugin.find_bracket_position: unused static method in beetsplug/ftintitle.py
• submit_albums(): unused standalone function in beetsplug/mbcollection.py (superseded by MBCollection.add_releases())
• NullPaddedInt: unused class in beets/dbcore/types.py (never imported or instantiated)

0 additions, 38 deletions across 4 files. We ran grep to do a second layer of verification.

To Do

This is a pure dead code cleanup (only deleted unused methods, functions and classes), so we believe documentation, changelog, and tests are not required.

• Documentation
• Changelog
• Tests

[github-actions]

Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.

[snejus]

Thanks!