WIP: COS-3382: renovate: switch RPM automerge from branch to PR

[c4rt0]

automergeType: "branch" required Renovate to push directly to main, which failed with GH006 because branch protection rules require 4 CI checks to pass.

Switching to "pr" lets Renovate open a pull request so all required checks run normally, then automerges when they pass.

Depends on: konflux-ci/mintmaker#597
See: https://issues.redhat.com/browse/COS-3382

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[coderabbitai]

Important

Draft PR not reviewed

Draft PRs are not automatically reviewed by default.

• Trigger a manual review

To automatically review draft PRs, update your CodeRabbit configuration:

reviews:
  auto_review:
    drafts: true

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