BREAKING CHANGE: rename ReadyToUse to SnapshotCaptured #1137

Job	Run time
build (3Mi, lock)	23m 25s
build (10Mi, various-transfer-part-size)	21m 31s
build (3Mi, change-to-standalone)	22m 38s
build (3Mi, full-backup)	33m 14s
build (3Mi, backup-failure)	33m 32s
build (3Mi, incr-backup)	38m 12s
build (3Mi, change-to-primary)	31m 40s
build (200Gi, various-transfer-part-size)	22m 59s
build (3Mi, change-to-secondary)	29m 10s
build (3Mi, !//)	45m 29s
	5h 1m 50s

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