Enable revert tests when possible, bump timeout

According the support matrix, the revert feature is enabled
for the following backends
- LVM/iSCSI: on all supported stable releases
- RBD: since Ussuri.

As the execution time of the lvm-lio test is around
the default time limit and it easily times out,
bump it to 3 hours.

Change-Id: I3350a9efa295fd03f48be919e3dd13477f6adc7a
1 file changed