lxd/project/permissions: Fixes AllowInstanceCreation tests
lxd/project/permissions: Fixes AllowInstanceCreation tests

Now that fetchProject returns all instance types, we can no longer use the length of the Instances slice to indicate how many containers we have.

This fixes a bug where the limits.virtual-machines limit would have only considered containers.

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

stgraber/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,atxwebs/lxd