[ilevkivskyi]

I know this is somewhat pedantic, but I cannot sleep well knowing we have this in our code. Few things here:

• Everywhere else in mypy first definition wins, not the last one, so we should do the same in presence of InitVar.
• Sorting strings is incorrect anyway, as it will put foo-redefinition-10 before foo-redefinition-9.
• Limit this special-case only to classes explicitly touched by plugins (as indicated by non-trivial metadata)

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅