Support building the split systemd repository

I plan to roll this out tomorrow (Friday), and then merge systemd into pmaports master (pmaports!5563 (merged)) :>

Depends on: pmbootstrap!2410 (merged)

• Related: #140 (closed)
• Close #144 (closed)
• Close #145 (closed) (staging repo + split repo should work as well)

changed milestone to %initial systemd support

assigned to @ollieparanoid

changed the description

mentioned in issue #140 (closed)

mentioned in merge request postmarketos.org!349 (merged)

added 71 commits

• 0ad20657...e36e77ba - 61 earlier commits
• 7159b7ec - data/templates: show splitrepos in html output (MR 119)
• 94930a2e - testdata/depends_systemd: add pkg to normal repo (MR 119)
• 97a68716 - test/bpo_test.raise_exception: set level to error (MR 119)
• 173a629d - job_callback.get_depends.get_payload: check splitrepo (MR 119)
• afb7bfe0 - job_callback.get_depends.get_payload: support pkg in 2 splitrepos (MR 119)
• 9fff7b5f - bpo.ui.log_repo_bootstrap/package: set splitrepo (MR 119)
• a8ffdd30 - job_services/local: support splitrepo in repo_wip_path (MR 119)
• 39751af7 - bpo/jobs/sign_index: don't get real index in test (MR 119)
• 0a98e804 - pyproject.toml: increase timeouts (MR 119)
• 5e75350e - test_repo_bootstrap_full: skip for pmbv2 (MR 119)

Compare with previous version

Some additional things:

• We will change the systemd mirror URL I guess? We can keep the staging repo as a symlink for now but new images should use a proper mirror directory without staging in the name.

maybe https://mirror.postmarketos.org/postmarketos/systemd/edge etc ?

• This needs to be changed in pmbootstrap, ideally we would have created the proper path as a symlink to the staging repo already but it's not the end of the world
• We should likely add a post-upgrade script to postmarketos-base-systemd that warns if the staging repo is in your /etc/apk/repositories file with instructions to fix, then in some weeks/months we can turn the warning into an error and then eventually remove the staging repo symlink

resolved all threads

enabled an automatic merge when all merge checks for 5e75350e pass

merged