drop patch trigger support
Being realistic, we are never going to test patches from mailing lists anymore.
The CKI pipeline is still going to report changed files from MRs via KCIDB patchset_files.
AC:
- remove patch support from triggers
- remove patch support from pipeline (outside of kcidb reporting of changed files)
- remove patch support from docs/images
- hunt for any other patch references
MRs:
Edited by Michael Hofmann