We added the eventlet executor waiting for taskflow to land and be ready
for us to consume it. Now that we have it, it's time to remove the
eventlet executor in favor of taskflow's parallel executors.
DocImpact
UpgradeImpact
Partially-implements blueprint: new-upload-workflow
Change-Id: I220a14b2a92949772d5322c9947c42e892cfdbfa