[bitnami/external-dns] Add targetLabels option to ServiceMonitor

[mrrsm]

Description of the change

Enables the ability to specify podTargetLabels and targetLabels on ServiceMonitor definitions to forward labels on prometheus

Benefits

Increased granularity on metrics

Possible drawbacks

Applicable issues

• fixes [bitnami/external-dns] Add targetLabels to the ServiceMonitor for external-dns #29332

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)