[bitnami/rabbitmq-cluster-operator] Add PodDistruptionBidget (PBDs)

[pinkavaj]

Description of the change

Add PodDisruptionBudget (PBD) to allow run the RabbitMQ Operator in HA mode. This is useful for production, because when the messaging-topology-operator pod is eg re-scheduled the validating-webhook cannot be called and this hinders cluster usability, if running only in single pod with no PDB.

Benefits

Reduces time when the usability of the K8s cluster is reduced.

Possible drawbacks

Adds PDB even when running in single pod mode, I see no issue with this, seems this is also default for most of the present charts.

Checklist

• Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
• Variables are documented in the values.yaml and added to the README.md using readme-generator-for-helm
• Title of the pull request follows this pattern [bitnami/<name_of_the_chart>] Descriptive title
• All commits signed off and in agreement of Developer Certificate of Origin (DCO)

[juan131]

Thanks for this great contribution! LGTM