tools/docker: install bazelisk instead of bazel #17713

Job	Run time
build	2m 20s
aux	3m 50s
race_dashboard	3m 31s
dashboard	2m 47s
race	9m 34s
gvisor	3m 50s
arch (presubmit_arch_openbsd)	3m 45s
arch (presubmit_arch_linux)	10m 33s
arch (presubmit_arch_freebsd)	6m 13s
arch (presubmit_arch_windows)	3m 35s
arch (presubmit_arch_netbsd)	3m 49s
arch (presubmit_arch_darwin)	3m 52s
arch (presubmit_arch_executor)	3m 16s
old	7m 0s
	1h 7m 55s

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