Update to 6.3

EDIT: I've dropped the 2 patches which made the blhc job not fail. The pipeline should fail and be fixed by someone who does know how to fix it.
EDIT 2: Updated to 6.3-rc1, details here
EDIT 3: Further updates may be done to either the rcX version as the rtY real-time patch set, but I'll only add a comment on that when it's noteworthy.
EDIT 4: Complete removal of Android patches may not be the best thing as Waydroid appears to benefit from that. Further investigation needed, hence Draft status. details here
EDIT 5: Reverted/undid my removal of the android patches. See here. Such changes should be done separately if needed/desired.
So removed the Draft status of this MR. Kernel is now updated to 6.3-rc3 + 6.3-rc3-rt4
EDIT 6: Updated to 6.3-rc4 + 6.3-rc4-rt6 and updated changelog timestamp to DST. This will likely be the last pro-active update I've pushed. I might do another one for (f.e.) 6.4-rc1. If there is an intention to merge this, feel free to ask for an update to the then latest version.
EDIT 7: Updated to the 6.3 release. There's a chance that tomorrow (morning in CEST) there will also be a rt update, but afaict the changes between rc7 and .0 are not that big, so maybe not.

EDIT 8: Updated to 6.3 + 6.3-rt11. But the big change is that @ukleinek fixed the blhc issue, so I'm removing my old 'research' notes.

In the changelog I put the 6.3 updates in a non-standard way, but the idea is that tomorrow 6.4-rc1 will be released and now it only needs to have a new line on top with "New upstream Release Candidate" (and an update in the version number ofc).
If reviewers want to have it differently, just let me know.