This is the tracking issue for the set of failures in provisional_202007271721_v20.1.4

#51952
#51953
#51954
#51955
#51956
#51957
#51958
#51960

They all fail with "has already been initialized" errors, and are all attributable to recent changes made to roachprod starting from #51329, where we changed it to explicitly initialize the cluster when starting node 1, when there's no cluster-bootstrapped file found on disk. For all these failing tests we seem to always be starting node 1 mid-test, where upon not finding the cluster-bootstrapped file on disk it expectedly failing to initialize the cluster and thus errors out. The tests that fail in this pattern are "mixed-version" tests, and given we're targeting the release-20.1 branch here, they all start off with nodes running 19.2 (never actually persisting the cluster-bootstrapped file on disk during bootstrap, which only happens when initializing a 20.1+ cluster).