Investigate Enabling HorizontalPodAutoscaler Resource in keycloak chart

The Keycloak chart comes with a HorizontalPodAutoscaler resource and we've confirmed that Keycloak does not need any extra configuration or values present to support multiple replcas: https://repo1.dso.mil/platform-one/big-bang/bigbang/-/blob/master/docs/understanding-bigbang/package-architecture/keycloak.md#high-availability

Test deploying keycloak with this HorizontalPodAutoscaler enabled via autoscaling.enabled and see if any of the autoscaling values need to be tuned or altered for better performance.

If no issues or other dependencies are required, enable this HorizontalPodAutoscaler for the package in BigBang so it is enabled by default.

• Deploy and test keycloak with HorizontalPodAutoscaler resource
• Document any caveats or recommendations in above linked package-architecture/keycloak.md#high-availability document
• Enable HPA in BigBang if no large caveats or recommendations are required