blocking things for inviting more pmOS+systemd testing

I'm using this issue to keep track of issues/MRs that would be good to complete before we send out any sort of broad invitation to the community to help test pmOS+systemd. I think it would be good to complete these things because they will make it easier for us to help test, and easier for us to make, review, and accept changes to the systemd-related stuff in pmOS.

• merge systemd staging branch into master #2773
  • Migrate pmaports CI to pmb 3.0 #3010 (closed)
    • implemented in !5344 (closed)
  • CI modifications for building systemd and non-systemd versions of packages
    • !5576 (merged)
  • Teach BPO to maintain multiple binary repos ( build.postmarketos.org#140)
  • Rename -service subpackages to -systemd: #2982 (closed)
• systemd service handling/auto-enabling #2937 (closed)
  • implemented in !5377 (merged)
• Better /usr merge support #2988 (closed)
• apk-tools fixes
  • upgrade fails #3075 (closed)
  • triggers don't work (!5513 (closed))

List of things formerly on the list, but removed (and why)

• automate forked package upgrades/syncing with Alpine aports #2790
  • why: nice to have, but it's a lower priority and we could use help solving it
• simplify adding files to systemd-services #3120
  • why: nice to have, but it's a lower priority and we could use help solving it