Remove converter assumption that everything is a promicro

[zvecr]

Description

Reduce the scenarios down to "valid" conversion targets. In the future, this will also allow configurator to only display converter drop-downs when applicable.

For example, the following will now correctly fail:

make xiudi/xd84:default CONVERT_TO=kb2040

Alternative could be to add just "pin_compatible": "promicro"? Ive scripted the changes so would be easy to adapt either way.

Types of Changes

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

[github-actions]

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