Unify the key up/down behaviour of RGB keycodes

[zvecr]

Description

Not 100% sure why there has to be a difference, as it pushes unnecessary context to intercepting with something like process_record_user.

it seems rather strange to have such a distinction within the codebase, when it doesn't exist for any other keycodes.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).