Extend Signin.Intercept.FRE.Event histogram

Having CTR data for this dialog is going to be useful as long as it
exists.

Fixed: 392616071
Change-Id: I4b21758adbafd863904f45d8e1d7566fecbefbb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6288512
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Commit-Queue: Amelie Schneider <amelies@google.com>
Auto-Submit: Alex Ilin <alexilin@chromium.org>
Reviewed-by: Amelie Schneider <amelies@google.com>
Cr-Commit-Position: refs/heads/main@{#1423128}