Revert "Fix branches used by kdesrc-build for qt5/kf5"
This reverts commit f0cc08dc.
Commit says: "we want 23.08 as the last qt5/kf5 based branch."
No we don't, because:
A) There's multiple qt5/kf5 based repos in KDE Gear release/24.02
B) For the repos in KDE Gear that are Qt6 based, "no qt5 branch exists anymore", we aren't doing any more releases, so maybe you want to build them, but that's on you, KDE is past them, so they shouldn't be mentioned here.