Various fixes for EL8 and Ubuntu 20.04
- Remove package building for EL8 and Ubuntu 20.04 based on this [1] upstream feedback
- Use EL7 packages for testing EL8 and Ubuntu 18.04 packages for 20.04
- Use a glob for package installation during testing so we don't have to workaround issues with $PLATFORM_VER on EL8 and Ubuntu 20.04
- Set $CINC_REF to unstable/cinc since this is currently working and a WIP
[1] https://github.com/chef/omnibus-software/pull/1250#issuecomment-692451217
Signed-off-by: Lance Albertson lance@osuosl.org