Don't trigger CI when pushing branches (elastic#240)

This commit stops triggering BK from triggering CI when branches get
pushed. We rely on CI for PRs, instead, which is handled by the BK PR
Bot.

Author: dliappis

catalog-info.yaml

@@ -58,7 +58,7 @@ spec:
       provider_settings:
         build_pull_requests: true
         build_pull_request_forks: false
-        build_branches: true
+        build_branches: false
         build_tags: false
         filter_enabled: true
         filter_condition: >-