Expose Medusa's GRPC server port config field

[sync-by-unito]

We’ve recently received a contribution to Medusa that allows configuring which port Medusa listens on when it runs as a GRPC service. This was hard-coded previously, and we had an user needing this to beconfigurable.

This ticket is about making a corresponding change in the k8ssandra-opeator that would expose this config option and allow k8ssandra-operator users configuring it.

┆Issue is synchronized with this Jira Task by Unito
┆Issue Number: K8OP-295