If user tries to get notification details before masakari-engine taskflow
driver add progress details of the first task of the recovery workflow,
it's giving Keyerror: 'progress_details'.
Fixed the issue by checking progress_details is available in the meta.
If it's not present, then get notification details will return empty list
of recovery_workflow_details.
Change-Id: I79af240d7715718b424695253ee452dc9552607d
Closes-Bug: #1819422
f2343ef09c