vault: Fix inaccurate comment
vault: Fix inaccurate comment

We never just leave a running Kelda Vault container untouched when
restarting Vault -- if one exists, we remove it and boot a fresh
container.

NetSys/quilt,NetSys/quilt,kelda/kelda,quilt/quilt,kklin/quilt,quilt/quilt,kklin/quilt,LuiseV/quilt,kklin/quilt,kklin/quilt,quilt/quilt,kklin/kelda,quilt/quilt,kelda/kelda,LuiseV/quilt,NetSys/quilt,LuiseV/quilt,kklin/kelda,NetSys/quilt,kelda/kelda,kelda/kelda,LuiseV/quilt,kklin/kelda,NetSys/quilt,LuiseV/quilt,kklin/kelda