test: don't rely on alloc runner update count
test: don't rely on alloc runner update count

We were incorrectly relying on the count of alloc updates in a number of
tests. Since alloc updates are async, their number is non-determinstic
and largely meaningless.

This should fix quite a few flaky tests in Travis and prevent future
mistaken assumptions in tests.

nak3/nomad,dvusboy/nomad,nak3/nomad,hashicorp/nomad,burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,nak3/nomad,dvusboy/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad,nak3/nomad,dvusboy/nomad,hashicorp/nomad,burdandrei/nomad,hashicorp/nomad,nak3/nomad,hashicorp/nomad,burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,burdandrei/nomad,nak3/nomad,dvusboy/nomad,nak3/nomad,dvusboy/nomad