all_types-itest: attempt to fix flakiness of verification
all_types-itest: attempt to fix flakiness of verification

This test seems to fail sometimes when it reads fewer rows than
expected. I'm guessing this is because it's reading from a follower,
and we don't properly manage safe-time to ensure that the read is
up to date.

This adds a ClusterVerfier check before counting the rows, such that
we wait until all replicas converge.

Change-Id: I97b5e0dcaca7d26143e42c9039f83032335a6ef5
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/8196
Tested-by: jenkins
Reviewed-by: David Alves <33ea948168c114d220e0372a903be6ee60f6396e@cloudera.com>

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