tests/ha: add late registration tests #518

Job	Run time
build-ceph	2m 3s
build	7m 49s
demo	4m 44s
discovery (container)	4m 38s
discovery (embedded)	4m 34s
pytest (cli)	12m 1s
pytest (state)	1m 48s
pytest (multi_gateway)	12m 0s
ha (sanity)	3m 43s
pytest (server)	12m 0s
ha (state_transitions)	3m 31s
pytest (grpc)	12m 6s
ha (state_transitions_both_gws)	4m 39s
pytest (omap_lock)	12m 0s
ha (state_transitions_loop)	11m 59s
pytest (old_omap)	12m 0s
ha (state_transitions_rand_loop)	11m 55s
pytest (log_files)	12m 0s
ha (late_registration)	12m 1s
pytest (nsid)	12m 2s
ha (late_registration_loop)	12m 0s
push-to-registry	1s
	3h 1m 34s

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