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.
2 jobs for <span class="ref-name">bjk/thanos_flags</span> in 50 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #190616300
rspec

00:00:50

 
  Lint
skipped #190616301
cookstyle
 
Name Stage Failure
failed
rspec Test
 * [new branch]      postgres-monitoring3    -> origin/postgres-monitoring3
* [new branch] postgres-uptime -> origin/postgres-uptime
* [new branch] pull-mirror-external-sla -> origin/pull-mirror-external-sla
* [new branch] revert-44c42771 -> origin/revert-44c42771
* [new branch] shouty -> origin/shouty
* [new branch] use-gitlabcom-for-berks -> origin/use-gitlabcom-for-berks
Checking out fecf7f82 as bjk/thanos_flags...
fatal: reference is not a tree: fecf7f82afeab9394a814b14ad0b0be1cddb4e08
ERROR: Job failed: exit code 1