dillon1000/react

Delete logTopLevelRenders flag and console timing (#9825)

This was mostly used for timing of initial mounts. However, we haven't
implemented that in Fiber and yet nobody has complained despite running
without it. Further more the update tracks any update within the tree,
not just updates to the props of the top level. This is much less useful
due to the variation.

I could make this track initial mounts too but it's a bit awkward so I'd
rather just delete it if possible. We can run the full profiling mode if
we want more coverage.