Dockerfile: Remove gcc package
Dockerfile: Remove gcc package

The gcc package is not needed because all the (test-)requirements
never depends on it.

Change-Id: I66646720554ef7562d9b654b5b4b049591c7d21b

redhat-cip/dci-control-server,redhat-cip/dci-control-server,enovance/dci-control-server,enovance/dci-control-server