Do not scan for vm locks when listing all machines.
Do not scan for vm locks when listing all machines.

Fixes: #4830
Signed-off-by: Warren Usui <021fe6d8989d7bdb08c8700d8c426ea80a140097@inktank.com>

t-miyamae/teuthology,caibo2014/teuthology,ivotron/teuthology,zhouyuan/teuthology,tchaikov/teuthology,dmick/teuthology,dreamhost/teuthology,yghannam/teuthology,SUSE/teuthology,yghannam/teuthology,robbat2/teuthology,dreamhost/teuthology,caibo2014/teuthology,SUSE/teuthology,dmick/teuthology,dmick/teuthology,ktdreyer/teuthology,ceph/teuthology,zhouyuan/teuthology,t-miyamae/teuthology,ivotron/teuthology,ceph/teuthology,michaelsevilla/teuthology,robbat2/teuthology,ktdreyer/teuthology,tchaikov/teuthology,SUSE/teuthology,michaelsevilla/teuthology