Allow cross cell promotion in PRS #308

Job	Run time
Set push variable	1s
Build and push vttestserver (mysql80)	1m 55s
Build and push lite (latest)	2m 0s
Build and push lite (percona80)	2m 21s
Build and push (bullseye, vtadmin)	1m 10s
Build and push (bullseye, vtorc)	37s
Build and push (bullseye, vtgate)	43s
Build and push (bullseye, vttablet)	37s
Build and push (bullseye, mysqlctld)	41s
Build and push (bullseye, mysqlctl)	41s
Build and push (bullseye, vtctl)	43s
Build and push (bullseye, vtctlclient)	42s
Build and push (bullseye, vtctld)	1m 13s
Build and push (bullseye, vtctldclient)	37s
Build and push (bullseye, logrotate)	24s
Build and push (bullseye, logtail)	17s
Build and push (bullseye, vtbackup)	42s
Build and push (bullseye, vtexplain)	44s
Build and push (bookworm, vtadmin)	1m 12s
Build and push (bookworm, vtorc)	40s
Build and push (bookworm, vtgate)	44s
Build and push (bookworm, vttablet)	41s
Build and push (bookworm, mysqlctld)	45s
Build and push (bookworm, mysqlctl)	42s
Build and push (bookworm, vtctl)	26s
Build and push (bookworm, vtctlclient)	29s
Build and push (bookworm, vtctld)	1m 15s
Build and push (bookworm, vtctldclient)	45s
Build and push (bookworm, logrotate)	22s
Build and push (bookworm, logtail)	32s
Build and push (bookworm, vtbackup)	27s
Build and push (bookworm, vtexplain)	41s
	25m 49s

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