[bitnami/postgresql] Allow backup pod to use DNS

[pixil98]

Description of the change

Allows the backup pod to use DNS which it requires to resolve the service it's backing up.

Benefits

Allows backups to work when storing the password as an environment variable

Possible drawbacks

None

Applicable issues

• fixes [bitnami/postgresql] Included networkpolicy blocks backup job from using dns #25438

Additional information

Backups are still broken when storing passwords in files

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)

[colin719]

need it, please merge it, thanks

[pixil98]

need it, please merge it, thanks

I’m ready to merge it as soon as @carrodher approves it.

[andresbono]

LGTM, thank you so much for your contribution!