Update `cta-frontend-grpc.conf.example` and `cta-frontend-grpc.service` and install config file with `cta-frontend-grpc` rpm

The example config file for the grpc frontend is missing some config options that are expected by FrontendService.cpp; as a result, filling in only the fields currently in the example is not enough to start up the frontend. The example systemd service file is still referencing obsolete options. In addition, since we changed the config file default location/name, we should install the example config file in the default location, as we do for the cta-frontend.

assigned to @kskovola

changed title from Update cta-frontend-grpc.conf.example to Update cta-frontend-grpc.conf.example{+ and cta-frontend-grpc.service+}

changed the description

mentioned in merge request !806 (merged)

changed title from Update cta-frontend-grpc.conf.example and cta-frontend-grpc.service to Update cta-frontend-grpc.conf.example and cta-frontend-grpc.service{+ and install config file with cta-frontend-grpc rpm+}

changed the description

closed with merge request !806 (merged)

mentioned in commit 769ff5df

mentioned in commit a04cbcec