apparmor="DENIED" for local build snap

[JamesLin]

If we build snap locally and install it directly on the clean machine, which doesn't have the publish release installed before. We will get error message like this:

```
error: cannot perform the following tasks:
- Start snap "openstack-hypervisor" (unset) services (systemctl command [start snap.openstack-hypervisor.ovs-vswitchd.service] failed with exit status 1: Job for snap.openstack-hypervisor.ovs-vswitchd.service failed because the control process exited with error code.
See "systemctl status snap.openstack-hypervisor.ovs-vswitchd.service" and "journalctl -xeu snap.openstack-hypervisor.ovs-vswitchd.service" for details.
)
```

And we can find some message in dmesg, which shows the apparmor="DENIED" (logs in attachment dmesg.txt)