Add threads dependency to test-process-util to fix C8s build

Limit parallelism when running tests to avoid hitting bug in python 3.6

Backport fix for #27287 (daemon-reload deadlock)

Backport fix for rlim_max

Gate out selinux-policy-base versioning for facebook
Move repart fixes to staging repo (#28479, #28812)

Backport 2 fixes for repart.

Update facebook support URL.

Bump release to 253.7.

Gate out systemd-selinux dependency on Facebook specific builds
Backport custom %clean implementation from rawhide
Backport selinux triggers logging revert from rawhide

Replace bpftool version requirement patch with sed so it works across systemd
Do selinux build in /tmp/selinux to avoid polluting source directory
Make sure we override existing output files when calling bzip2.

Use the 8 macro for checks instead of explicitly checking against 1.

Add back python3-zstd on c9s now that it's been added to EPEL 9
Add back support for c8s builds (without ukify)
Add full backport of bpftool version requirement lowering

Condition out python3-zstd until it is added to EPEL

Sync from Fedora rawhide 5982ae9504c8f2697a839c6ce2a82287a60c1043

Backport https://github.com/systemd/systemd/pull/25385

Remove selinux bcond in favor of boolean dependency on selinux-policy so that
selinux is only installed if selinux-policy is installed
Add selinux file contexts for /efi
Remove policycoreutils-python-utils dependency from systemd-selinux