Do not check host/storage tags on stopped router vm

[remibergsma]

Error seen:

Note: Router r-939-VM has state Stopped
Error: your current cluster has hosts with tags 'systemvm'. Migration will only work when current cluster is in Disabled state and has the host tag 'systemvm' removed.

But router is stopped so doesn't make sense. This is due to "false" returned by checkClusterHostTags.

Via @fborn