gha: use ssh -tt to have a tty
gha: use ssh -tt to have a tty

Github Actions execution environments lack tty, which is needed for
integration tests. We have used script utility before to provide a fake
tty, but it appears to be buggy on CentOS 7.

Since we use ssh anyway to access Vagant VM, add -tt to forcefully
allocate a tty.

Apparently, neither "TERM=xterm" nor "stty size" is needed for
any tests to work, so remove those, too.

Finally, unit tests do not need a terminal, so remove the "script"
from those.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

kolyshkin/runc,opencontainers/runc,kolyshkin/runc,dqminh/runc,opencontainers/runc,rhatdan/runc,estesp/runc,rhatdan/runc,estesp/runc,kolyshkin/runc,dqminh/runc,rhatdan/runc,rhatdan/runc,estesp/runc,dqminh/runc,opencontainers/runc,opencontainers/runc,dqminh/runc,kolyshkin/runc