BREAKING CHANGE: rename ReadyToUse to SnapshotCaptured #905

Job	Run time
build (3Mi, backup-failure)	31m 26s
build (3Mi, incr-backup)	33m 32s
build (3Mi, full-backup)	26m 51s
build (3Mi, change-to-primary)	28m 28s
build (3Mi, change-to-standalone)	24m 8s
build (3Mi, change-to-secondary)	27m 4s
build (200Gi, various-transfer-part-size)	22m 39s
build (10Mi, various-transfer-part-size)	22m 47s
build (3Mi, !//)	38m 11s
	4h 15m 6s

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