fix(opensearch-dashboards) - use selectorLabels

[rcomanne]

Description

Use the actual selectorLabels as generated.

Issues Resolved

487

Check List

• [ ] Commits are signed per the DCO using --signoff

For any changes to files within Helm chart directories:

• [ ] Helm chart version bumped Not sure if this can be a minor (2.15.0) or should be a major, as it includes a breaking change. When selector labels change, current resources need to be removed before they can be recreated.,
• [x] Helm chart CHANGELOG.md updated to reflect change

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[rcomanne]

Closing for another with DCO.