Add Release Notes disclaimer only for PRs

[MaciejKaras]

Summary

Previously we were adding the disclaimer also for master commits, which can be misleading -> https://github.com/mongodb/mongodb-kubernetes/actions/runs/18402911248/attempts/1#summary-52436112489

Proof of Work

Workflow validation is enough.

Checklist

• Have you linked a jira ticket and/or is the ticket in the title?
• Have you checked whether your jira ticket required DOCSP changes?
• Have you added changelog file?
  • use skip-changelog label if not needed
  • refer to Changelog files and Release Notes section in CONTRIBUTING.md for more details

[github-actions]

⚠️ (this preview might not be accurate if the PR is not rebased on current master branch)

MCK 1.5.0 Release Notes

New Features

• Improve automation agent certificate rotation: the agent now restarts automatically when its certificate is renewed, ensuring smooth operation without manual intervention and allowing seamless certificate updates without requiring manual Pod restarts.

Bug Fixes

• MongoDBMultiCluster: fix resource stuck in Pending state if any clusterSpecList item has 0 members. After the fix, a value of 0 members is handled correctly, similarly to how it's done in the MongoDB resource.
• MultiClusterSharded: Blocked removing non-zero member cluster from MongoDB resource. This prevents from scaling down member cluster without current configuration available, which could lead to unexpected issues.