scripts/make-packaging-target: Rename the password_rhel8 argument.

Give it a better name, that will allow passing any extra arguments
required at 'docker build' time.  Also factorize the common docker run
options string for the various RPM-based systems.

GitLab: #264
Change-Id: I71d81d8dc7639091dfba7b52e2f6f9dd98003914