tests: Updates .gitignore to ignore test build artefacts
tests: Updates .gitignore to ignore test build artefacts

Signed-off-by: tomponline <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

ss1h2a3tw/lxc,hallyn/lxc,ss1h2a3tw/lxc,ss1h2a3tw/lxc,hallyn/lxc,hallyn/lxc