[bitnami/postgresql-ha] fix POSTGRES_POSTGRES_PASSWORD env var when generating secrets

[davidfrickert]

Description of the change

When using a username that is not "postgres" and no credentials or existingSecret is passed via values, POSTGRES_POSTGRES_PASSWORD env var needs to be passed to postgres pod.
This PR fixes a condition that should not have been negated, so that when username is not "postgres" and credentials are generated, we pass the env var to the pod.

Applicable issues

• fixes [bitnami/postgresql-ha] Chart does not work properly without setting pg credentials via values or using existingSecret #30105

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)

[javsalgar]

Hi!

Thank you so much for the PR! Could you bump the chart patch version?

[davidfrickert]

Hi!

Thank you so much for the PR! Could you bump the chart patch version?

Hi, no worries!
Done