[bitnami/mongodb] feat: allow setting `targetLabel` and `podTargetLabels` array on ServiceMonitor

Description of the change

This update to MongoDB chart will allow users to set targetLabels and podTargetLabels arrays on ServiceMonitor resource in the chart. By default, the arrays are set empty and there is a check in the ServiceMonitor file to only put these array if they are set and array is not empty.

Spec ref: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#servicemonitorspec

Benefits

Allows users to further enrich Prometheus metrics with new labels when they are scraped by the server.

Possible drawbacks

None

Applicable issues

None

Additional information

Checklist

[x] Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
[x] Variables are documented in the values.yaml and added to the README.md using readme-generator-for-helm
[x] Title of the pull request follows this pattern [bitnami/] Descriptive title
[x] All commits signed off and in agreement of Developer Certificate of Origin (DCO)

bitnami / charts