Support invoking install.sh on SLE Micro with or without SELinux
enabled. Same deal for SLES.

Additionally, easy-to-invoke assertions, via Vagrant, that the local
install.sh works correctly:
- tests/install/centos-7 (stand-in for rhel 7)
- tests/install/centos-8 (stand-in for rhel 8)
- tests/install/opensuse-leap (stand-in for sles)
- tests/install/opensuse-microos (stand-in for sle-micro)
- tests/install/ubuntu-focal

Addresses #3188
Addresses #3917
Signed-off-by: Jacob Blain Christen <jacob@rancher.com>