chore(ci): migrate Linux CI to runs-on self-hosted runners #5976

Job	Run time
build-wheels-free-threaded	2m 4s
build-wheels	2m 0s
check-xarray-docs	13s
test-free-threaded	2m 9s
xarray-backends (minimum, 2025.07.1, 3.1.0)	1m 22s
test (latest, latest-release, latest-release, latest-release, latest-release)	1m 41s
stubtest	18s
test-hypothesis-shard (2)	2m 7s
compat-stateful	2m 6s
test-hypothesis-shard (0)	49s
test (minimum, 2025.07.1, 2025.2.0, 2025.2.0, 3.1.0)	1m 54s
test-hypothesis-shard (1)	2m 9s
xarray-backends (latest-release, latest-release, latest-release)	1m 27s
test-hypothesis	4s
	20m 23s

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