CI: move all workflows to repository runners #455

Job	Run time
Preset matrix (smoke, self-hosted macOS) (2)	12m 39s
Preset matrix (smoke, self-hosted macOS) (4)	2m 40s
Specialised + canvas smoke	15m 16s
Preset matrix (smoke, self-hosted macOS) (3)	15m 16s
Preset matrix (smoke, self-hosted macOS) (1)	15m 16s
Mini-train matrix (macOS, nightly)	-9s
Matrix report	15s
	1h 1m 13s

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