Fix instance directory path for lxc

Commit 12b8bd380e22a40e10e9d2758f5a0d594517de51 triggers a regression
when starting a STOPPED LXC instance. Instance referecne is needed to
correctly setup container rootfs path.

Change-Id: Id55b7f3a631e80a0da3f52c55784414105a61142
Merge "Fix instance directory path for lxc"