[DOM] Blur portaled Fragment focus targets (#37161)

focus() passes through portals as it attempts focus down the fiber tree.
blur() exited early based on a containment check, causing it to stop at
portals.

The result could be a focused element that cannot be blurred.

Follow up to https://github.com/react/react/pull/37125, which made
blur() apply recursively to be consistent with focus().