ci: bump Alpine to 3.18
What does this MR do and why?
Uprev to recent Alpine 3.18:
- use recent LLVM 16
- cleanup the coding style and fix container which at some point of 3.17 release stopped generating correctly (I assume some dependency changes got tuned from Alpine side).
Currently running stress-tests, after ~ 20, I'll assign to Marge.
Signed-off-by: David Heidelberg david.heidelberg@collabora.com