dillon1000/react

Reset new fork to old fork (#20254)

* Fix typo

This typo was fixed in the new fork but not the old.

* Reset new fork to old fork

Something in the new fork is causing a topline metrics regression. We're
not sure what it is, so we're going to split it into steps and bisect.

As a first step, this resets the new fork back to the contents of the
old fork. We will land this to confirm that the fork infra itself is
not causing a regression.

* Fix tests: Add `dfsEffectsRefactor` flag

Some of the tests that gated on the effects refactor used the `new`
flag. In order to bisect, we'll need to decompose the new fork changes
into multiple steps.

So I added a hardcoded test flag called `dfsEffectsRefactor` and set it
to false. Will turn back on when we switch back to traversing the
finished tree using DFS and `subtreeTag`.