improvement(k8s-local): cache docker images only on fresh setups
improvement(k8s-local): cache docker images only on fresh setups

For the moment we cache docker images all the time even
running on an already existing cluster having "reuse_cluster=1"
option set.

So, skip "docker images caching" operations for reused clusters
to reduce time we spend for init test.

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests