ci(spanner): use airlock for fetching dependencies #10023

Job	Run time
dependencies (17)	1m 15s
units (11)	3m 30s
units (17)	3m 25s
units (21)	3m 27s
units (8)	3m 31s
units-with-multiplexed-session (11)	3m 59s
units-with-multiplexed-session (17)	3m 41s
units-with-multiplexed-session (8)	15m 50s
units-with-multiplexed-session (21)	3m 32s
windows	6m 31s
clirr	1m 34s
javadoc	2m 34s
lint	1m 36s
	54m 25s

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