prow: Drop some plugins from coreos/rpm-ostree

Most notably drop approve and lgtm, which are responsible
for a lot of comment spam.  We are going to experiment
with using the Github-native methods for this.

xref coreos/fedora-coreos-tracker#764

core-services/prow/02_config/_config.yaml

@@ -47,12 +47,6 @@ branch-protection:
     coreos:
       repos:
         rpm-ostree:
-          branches:
-            master:
-              protect: true
-              required_status_checks:
-                contexts:
-                - continuous-integration/jenkins/pr-merge
           protect: false
     cri-o:
       required_status_checks:
@@ -797,7 +791,6 @@ tide:
     - containers/podman
     - coreos/bootupd
     - coreos/coreos-assembler
-    - coreos/rpm-ostree
     - integr8ly/ansible-tower-configuration
     - integr8ly/application-monitoring-operator
     - integr8ly/cloud-resource-operator

core-services/prow/02_config/_plugins.yaml

@@ -132,7 +132,6 @@ approve:
   lgtm_acts_as_approve: true
   repos:
   - coreos/bootupd
-  - coreos/rpm-ostree
   require_self_approval: false
 - commandHelpLink: https://go.k8s.io/bot-commands
   lgtm_acts_as_approve: true
@@ -3857,22 +3856,16 @@ plugins:
     - yuks
   coreos/rpm-ostree:
     plugins:
-    - approve
     - assign
-    - blunderbuss
     - cat
     - dog
     - heart
-    - golint
     - help
     - hold
     - label
-    - lgtm
-    - lifecycle
     - override
     - retitle
     - shrug
-    - sigmention
     - skip
     - trigger
     - verify-owners