Add priorityClassName to Helm Charts - Issue #1143

[aglees]

Checklist

• The title of the PR is clear and informative
• If applicable, the changes made in the PR have proper test coverage
• Issues addressed by the PR are mentioned in the description followed by Fixes.

Description

Add an option in the Helm Chart for priorityClassName

Fixes

This addresses the feature request #1143

[ghost]

All CLA requirements met.

[akshaysngupta]

@aglees can you add a helm render test.

1. Update this file with the new parameter.
2. Set env variable export RENDER_SNAPSHOTS="true"
3. You can then check by running go test ./... in the folder.
4. Check and Commit the snapshot