go/vt/mysqlctl: add postflight_mysqld_start and preflight_mysqld_shut… #614

Job	Run time
Build and push lite (latest)	4m 38s
Build and push vttestserver (mysql80)	2m 47s
Build and push lite (mysql84)	4m 38s
Build and push vttestserver (mysql84)	3m 7s
Build and push lite (percona80)	4m 35s
Build and push (bullseye, vtadmin)	1m 35s
Build and push (bullseye, vtorc)	1m 2s
Build and push (bullseye, vtgate)	1m 11s
Build and push (bullseye, vttablet)	1m 9s
Build and push (bullseye, mysqlctld)	55s
Build and push (bullseye, mysqlctl)	1m 1s
Build and push (bullseye, vtctl)	1m 7s
Build and push (bullseye, vtctlclient)	1m 5s
Build and push (bullseye, vtctld)	1m 37s
Build and push (bullseye, vtctldclient)	57s
Build and push (bullseye, logrotate)	26s
Build and push (bullseye, logtail)	34s
Build and push (bullseye, vtbackup)	1m 2s
Build and push (bullseye, vtexplain)	1m 2s
Build and push (bookworm, vtadmin)	1m 36s
Build and push (bookworm, vtorc)	1m 5s
Build and push (bookworm, vtgate)	1m 9s
Build and push (bookworm, vttablet)	1m 9s
Build and push (bookworm, mysqlctld)	1m 1s
Build and push (bookworm, mysqlctl)	54s
Build and push (bookworm, vtctl)	1m 7s
Build and push (bookworm, vtctlclient)	1m 12s
Build and push (bookworm, vtctld)	1m 47s
Build and push (bookworm, vtctldclient)	1m 10s
Build and push (bookworm, logrotate)	29s
Build and push (bookworm, logtail)	45s
Build and push (bookworm, vtbackup)	1m 7s
Build and push (bookworm, vtexplain)	1m 13s
Slack Notification if failed	0s
	50m 12s

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