cluster-merge: consider file storage enable state
cluster-merge: consider file storage enable state

There's no point in checking whether the file storage dir in the two
clusters is the same if file storage is not even enabled

Signed-off-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>
Reviewed-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>

andir/ganeti,yiannist/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,yiannist/ganeti,leshchevds/ganeti,mbakke/ganeti,bitemyapp/ganeti,yiannist/ganeti,dimara/ganeti,apyrgio/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,leshchevds/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/snf-ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,mbakke/ganeti,ganeti/ganeti,andir/ganeti,apyrgio/ganeti,onponomarev/ganeti,mbakke/ganeti,dimara/ganeti,andir/ganeti,ganeti/ganeti,leshchevds/ganeti