Hide tab where password change happens

Before this CL: password change is performed in the background tab
After this CL: password change is performed in the unattached WebContents. When necessary it's attached back to the tab strip where
the original tab is.

Bug: 415923860
Change-Id: Ic7959fbfb9bf180eaf05273d7fd131d1cb0050cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6509009
Auto-Submit: Viktor Semeniuk <vsemeniuk@google.com>
Reviewed-by: Maria Kazinova <kazinova@google.com>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Viktor Semeniuk <vsemeniuk@google.com>
Cr-Commit-Position: refs/heads/main@{#1458760}