[CI/CD] Switch Jenkinsfile to use libvirt and only one host (#3804)

Summary of changes:
Deploy Vagrant using libvirt instead of virtualbox (for nested virt)
Removed logic using ssh to connect to another host
Removed logic related to git clone tarball
Removed command output being saved to log files (Jenkins log shows it now)
cppcheck Docker container mounts git dir instead of using tarball
OAI opanair-epc-fed git repo is now cloned instead of depended on by external scripts
oai-spgwc and oai-spgw-tiny Docker images are built if not present on Jenkins node

Signed-off-by: Matthew Mosesohn <matthew.mosesohn@gmail.com>