[iOS] Update the string for the delete all data button confirmation
dialog.

The current string has nested plural which is not supported by google
translation team go/plurals#nesting-plurals. This UX change is confirmed by the PMs.

Bug:394047369

Change-Id: Ibe44f6f5e3e3fdf592a48c2af57984d83540c7ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6234524
Reviewed-by: Ernesto Izquierdo Clua <eic@google.com>
Reviewed-by: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Xu Li <mxlg@google.com>
Reviewed-by: Alexis Hétu <sugoi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1416554}
NOKEYCHECK=True
GitOrigin-RevId: 26ac90c274e061c4cdec23439e5cc8435f3713b9