Fix error contain checks in vtgate package #862

Job	Run time
Set push variable	1s
Build and push vttestserver (mysql80)	1m 49s
Build and push lite (latest)	2m 10s
Build and push lite (percona80)	2m 11s
Build and push (bullseye, vtadmin)	1m 10s
Build and push (bullseye, vtorc)	45s
Build and push (bullseye, vtgate)	39s
Build and push (bullseye, vttablet)	42s
Build and push (bullseye, mysqlctld)	38s
Build and push (bullseye, mysqlctl)	37s
Build and push (bullseye, vtctl)	38s
Build and push (bullseye, vtctlclient)	24s
Build and push (bullseye, vtctld)	1m 16s
Build and push (bullseye, vtctldclient)	36s
Build and push (bullseye, logrotate)	14s
Build and push (bullseye, logtail)	26s
Build and push (bullseye, vtbackup)	44s
Build and push (bullseye, vtexplain)	40s
Build and push (bookworm, vtadmin)	1m 11s
Build and push (bookworm, vtorc)	29s
Build and push (bookworm, vtgate)	26s
Build and push (bookworm, vttablet)	25s
Build and push (bookworm, mysqlctld)	30s
Build and push (bookworm, mysqlctl)	50s
Build and push (bookworm, vtctl)	46s
Build and push (bookworm, vtctlclient)	35s
Build and push (bookworm, vtctld)	1m 9s
Build and push (bookworm, vtctldclient)	42s
Build and push (bookworm, logrotate)	27s
Build and push (bookworm, logtail)	28s
Build and push (bookworm, vtbackup)	42s
Build and push (bookworm, vtexplain)	46s
	25m 6s

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