[CI/BK] Disable code triggers for fleet daily (#181901)

## Summary
the job was intended to run 1x day - but due to default values, it was
getting triggered on every commit & elastic/kibana branches

.buildkite/pipeline-resource-definitions/kibana-fleet-packages-daily.yml

@@ -28,6 +28,7 @@ spec:
       pipeline_file: .buildkite/pipelines/fleet/packages_daily.yml
       skip_intermediate_builds: false
       provider_settings:
+        trigger_mode: none
         publish_commit_status: false
         prefix_pull_request_fork_branch_names: false
         skip_pull_request_builds_for_existing_commits: false