[Umbrella] Collect optimization Suggestions/Ideas and phrase out CoPilot Instructions for actually doing the optimization work

[KlausLoeffelmann]

Let's collect as list of optimization Issues, where we start phrasing out CoPilot instructions, so that the actual refactoring work can be done by CoPilot, which leaves us more time to concentrate on important domain-specific optimization or feature work.

• [ ] ColorMatrix refactoring optimization, as suggested by @JeremyKuhne in https://github.com/dotnet/winforms/pull/13360#discussion_r2082489003