Merge pull request #165 from cybozu-go/implement-metrics #823

Job	Run time
build (3Mi, full-backup)	31m 43s
build (3Mi, incr-backup)	30m 44s
build (3Mi, backup-failure)	30m 35s
build (3Mi, change-to-secondary)	26m 52s
build (10Mi, various-transfer-part-size)	26m 30s
build (3Mi, change-to-primary)	26m 42s
build (3Mi, change-to-standalone)	27m 27s
build (3Mi, !//)	37m 49s
build (200Gi, various-transfer-part-size)	20m 50s
	4h 19m 12s

Provide feedback