[bitnami/cert-manager] Enable PodDisruptionBudgets

[fmulero]

Description of the change

Enabled PodDisruptionBudget by default and little fixes in PDB configuration to keep it aligned with current templates.

Benefits

PDB protects our applications from voluntary disruption initiated by cluster administrators.
Keep our charts up to date according to our templates.

Possible drawbacks

None

Adition information

• Pod disruption budgets
• Specifying a Disruption Budget for your Application

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)