Reland "Add UMA metrics for Youtube subframe re-auth interstitial"

This reverts commit c65f29cb.

Reason for revert: A test condition (re-authentication completed)
was flaky or completely failing in some builders. This is now
removed and it can be added back only when we have a suitable
way to wait for the interstitial to be replaced first.

Original change's description:
> Revert "Add UMA metrics for Youtube subframe re-auth interstitial"
>
> This reverts commit 0966ddf5.
>
> Reason for revert: breaks CI bot "Linux Tests (Wayland)"
>
> Original change's description:
> > Add UMA metrics for Youtube subframe re-auth interstitial
> >
> > NO_IFTTT=Fixing a typo in FamilyLinkUserReauthenticationInterstitialState, no functional change.
> >
> > Bug: 374254038
> > Change-Id: Id75da9967f760e27c586ce0eef53a2ada13082d8
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5966313


> > Reviewed-by: James Lee <ljjlee@google.com>
> > Commit-Queue: Anthi Orfanou <anthie@google.com>
> > Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
> > Reviewed-by: Duong Dac <ddac@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#1378277}
>
> Bug: 374254038
> Change-Id: I490d92fca601d0ddf27a3b54d80a826fb7d17739
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5994310
> Owners-Override: Titouan Rigoudy <titouan@chromium.org>
> Auto-Submit: Titouan Rigoudy <titouan@chromium.org>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Commit-Queue: Titouan Rigoudy <titouan@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1378353}

Bug: 374254038
Change-Id: Ia5f554edf7f22e8acc16460b08b95e2a8ca655ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5994213


Reviewed-by: James Lee <ljjlee@google.com>
Commit-Queue: Anthi Orfanou <anthie@google.com>
Cr-Commit-Position: refs/heads/main@{#1378932}