The test "should not change the subpath mount on a container restart if the environment variable changes"
creates a pod with the liveness probe: cat /volume_mount/test.log. The test then
deletes that file, which causes the probe to fail and the container to be restarted.
After which it recreates the file by exec-ing into the pod, but there is a chance
that the container was not created yet, or it did not start yet.
This commit adds a few retries to the exec command.
06a1b7b491