[Merged by Bors] - Use dedicated PoST service for Proof generation #15074

Job	Run time
filter-changes	9s
lint	3m 8s
quicktests	1m 39s
unittests (ubuntu-latest)	11m 21s
build (ubuntu-latest)	1m 25s
unittests (macos-latest)	11m 12s
build (self-hosted, linux, arm64)	18s
unittests (self-hosted, macos, arm64)	11m 6s
build (macos-latest)	1m 21s
unittests-slower (self-hosted, linux, arm64)	15m 7s
build (self-hosted, macos, arm64)	53s
unittests-slower (windows-latest)	24m 18s
build (windows-latest)	6m 0s
ci-status	2s
	1h 27m 59s

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