Fix TestGlobalResyncOnConfigMapUpdate flakiness (#3148)
Fix TestGlobalResyncOnConfigMapUpdate flakiness (#3148)

* Revert "Another attempt at stabilizing global resync tests. (#3172)"

This reverts commit 352fcddb9c75b39815e84a39a41fc21d30a7f570.

* Fix TestGlobalResyncOnConfigMapUpdate flakiness

Split into two tests to make callbacks less awkward.

Trigger global resync after deployments creation to avoid a race.

knative/serving,knative/serving