after upgrading gerrit to ver 2.8, review.o.o will have a new label called 'Workflow'
that combines approved and wip labels. Updating the trigger to match the label.
We need to keep the 'approved' label so it will continue to work with gerrit ver 2.4.4
The gerrit workflow label is defined as:
[label "Workflow"]
function = MaxWithBlock
value = -1 Work in progress
value = 0 Ready for reviews
value = +1 Approved
Note: This same change has already been applied and tested on review-dev.o.o
Ieb7e2dde49cd64f2aa3dbf939c391492d73ed886
Partial-Bug: #1082781
Change-Id: I849eca5f5c20a21ad0007541ea60c82e2da343e0