[bitnami/prometheus] Add environment variable support to the Prometheus Thanos container

[james-mchugh]

Description of the change

• Adds ability to configure environment variables for the Prometheus Thanos container.
• Adds ability to use templating in the secret name used for Thanos' storage config secret

Benefits

Users can mount secrets via environment variables to the container, enabling setting environment variables like AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY to securely mount existing secrets in the cluster to the container.

Additionally, the secret name supporting templating is a common pattern for many secret and configmap names. It allows for dynamic configurations of the secret name, which is often useful for umbrella charts that may wrap this chart.

Possible drawbacks

Applicable issues

Additional information

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)

[github-actions]

This Pull Request has been automatically marked as "stale" because it has not had recent activity (for 15 days). It will be closed if no further activity occurs. Thank you for your contribution.

[james-mchugh]

Sorry to ping you @javsalgar and @alvneiayu, but please let me know if there is anything I can do to help get this PR merged sooner.

[github-actions]

This Pull Request has been automatically marked as "stale" because it has not had recent activity (for 15 days). It will be closed if no further activity occurs. Thank you for your contribution.