The CI will be happy with pinned build environments, we can use github cache for the container if nothing changes. Removes 1hr github.com/plowsof/monero-gui/actio…ns/runs/11214059421/job/31168368362

Threads=4 instead of 3 too

1~ min build instead of 10mins xD

Oops. There is no 1min vs 10.build.diff, but still great