Fix: Add blackpill-f4 to meson CI

[ALTracer]

Detailed description

• After the removal of makefiles, none of the blackpill-f4 binary firmware autobuilds survived. This creates two problems: users can't get a prebuilt image from main CI; and contributors do not get platform-specific code checked by PR CI.
• This PR adds the three blackpill-f4 flavours as-is from cross-files to build-linux probe matrix in both workflows.

size-diff pass does not produce a downloadable artifact. scripts/meson-build-all.sh is unused.

I noticed you've got 5 flavours of native now, but I'm not adding them to build-PR.yml, because target driver code is checked on other adapter builds, and platform code can be checked once per platform.

Finally, I'm adding the four newly added/extracted and hence disabled groups of targets (apollo3.c; ch32,gd32,mm32 in stm32f1.c) to blackpill-f4 cross-files such that size-diff reflects their impact on binary size. Please confirm whether this needs to be expanded to all other big flash platforms.

Your checklist for this pull request

• [x] I've read the Code of Conduct
• [x] I've read the guidelines for contributing to this repository
• [x] It builds for hardware native (see Building the firmware)
• [x] It builds as BMDA (see Building the BMDA)
• [x] I've tested it to the best of my ability
• [x] My commit messages provide a useful short description of what the commits do

Closing issues

[ALTracer]

Rebased. Inaccuracy: the 5 flavours of native are NOT built per build-and-upload.yml triggered by pushes to main. But they are built for PR sync-pushes. Is this what you intended? I'm not touching those here, but sounds like users might expect native fw on main, too?

[dragonmux]

It is not what we intended and that is in fact another oversight on our part. If you wanted to include adding those flavours to build-and-upload before we merge, that would be most welcome.

[ALTracer]

Added 4 lines to the other CI matrix. Please check the commit message. Extends and/or fixes #1968, I think.