skyloong/gk61: Remove overriding of core keycode behaviour

[zvecr]

Description

Keyboards should not override keycodes like TO(x) to behave like PDF(x).

Also,

• Partially indicator logic as was dependent on overriding keycode behaviour
  • Also made bad assumptions on configuration of keymap which user changes can invalidate
• Aligned implementations between the two pro revisions
• Remove some unused defines

Types of Changes

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

Issues Fixed or Closed by This PR

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).