Utilities/Release: Add docker spec for STGZ package on Linux

The spec added by commit facc240a (Utilities/Release: Add docker specs
to build and test Linux binaries, 2019-08-23) generates only the TGZ
package, but the old `Utilities/Release/linux64_release.cmake` script
also generated a STGZ package.
6 jobs for docker-rel-linux
Status Job ID Name Coverage
  External
passed ghostflow-check-master

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager