[bitnami/elasticsearch] PDB review

[fmulero]

Description of the change

Little fixes in PodDisruptionBudget configuration to keep it aligned with current templates.

Benefits

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)

[fmulero]

Not needed