* Revert "Skip jest tests that timeout waiting for react"

This reverts commit dd9b0b3.

* Unmount async effectful components instead of waiting for them

A previous commit introduced waitForUpdates as a solution to the
warnings introduced by enzymejs/enzyme#2073:
by waiting for the effects to complete we avoid the warning.

However, waiting for the effects to complete could occasionally be very
costly, especially on an overtasked CI machine, and I've been seeing
these tests fail on occasion due to timeouts.

Since a warning message is preferable to a false negative, I'm removing
waitForUpdates and allowing the warnings to occur, as this should be
fixed on a subsequent update of enzyme/react-adapter.

I've also fixed warnings in a few particularly problematic/noisy tests
by simply unmounting the component at the end of the test (this does
not work in an afterEach).