Remove noinline directives from new commit phase (#20241)

My theory for too much inlining contributing to overall stack size is
likely flawed, because Closure reuses variables within a function to
optimize registers.

Even if my theory were correct, the impact would be minimal anyway
because the recursive implementation of the commit phase traversals is
behind a disabled feature flag.

Going to revert this. We can maybe test the impact once we land the
commit phase changes. In the meantime, I'd prefer to eliminate this
delta from the new fork.