feat: Add PodDisruptionBudget for stateless apps

[mani-thumu]

Add Pod Disruption Budget (PDB) support to 7 stateless services to improve high availability and graceful pod disruption handling.

Services updated:

• catalog-server
• radar-self-enrolment-ui
• radar-grafana
• radar-rest-sources-authorizer
• radar-gateway
• radar-output
• radar-push-endpoint

Changes for each service:

• Added templates/poddisruptionbudget.yaml template with minAvailable: 1 (default safety level)
• Added podDisruptionBudget configuration section to values.yaml with enabled flag and configurable minAvailable/maxUnavailable

Benefits

• Ensures at least one pod remains available during voluntary disruptions (node drains, cluster operations)
• Allows operators to configure scaling and disruption policies per deployment
• Foundation for future HA (high availability) and HPA configurations
• Consistent PDB implementation across all stateless services

HPA implementation will be added separately after team discussion.

Checklist

• Chart version bumped in Chart.yaml according to semver.
• Variables are documented in the README.md (auto-generated by helm-docs)
• Title of the PR starts with chart names

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching charts/*/values.yaml:

• Is the PR adding a new container? Please reviewer, add it to the models (internal process)
• Is the PR adding a new parameter? Please, ensure it’s documented in the README.md

This is an automatically generated QA checklist based on modified files.