Since the recent core-updates merge, I've seen the build coordinator
using less memory, but it's also been crashing in a new way, up to 10
times a day.

In the log, you see something like:

  2023-05-07 09:15:42 Signals delivery fails constantly at GC #71051
  2023-05-07 09:15:42 Signals delivery fails constantly

I'm guessing the switch from libgc-8.0.4 to libgc-8.2.2 has something to
do with this.