Tune additional Thanos flags

* Disable gossip cluster now that we're using discovery.
* Enable partial response in order to avoid hanging on slow storage
requests.
* Enable debug level logs on the storage servers.
2 jobs for <span class="ref-name">bjk/thanos_flags</span> in 3 minutes and 25 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #190617189
rspec

00:01:55

 
  Lint
failed #190617190
cookstyle

00:01:29

 
Name Stage Failure
failed
cookstyle Lint

Offenses:

attributes/thanos.rb:45:1: C: Missing space after #.
#default["thanos-query"]["flags"]["store.response-timeout"] = "2s"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

22 files inspected, 1 offense detected
ERROR: Job failed: exit code 1