Update builder image and RHGitaly configuration to spawn Mercurial subprocesses
As this MR also contains the base image bump, we're running the full pipeline to check that everything will be ok with the future 17.0.0rc
This instance will be upgraded to Heptapod 17.5.0rc1 on 2024-10-24 between 18:00 and 19:00 UTC+2
As this MR also contains the base image bump, we're running the full pipeline to check that everything will be ok with the future 17.0.0rc