Refactor and add ShouldPreventAutofillFromOverridingPrefilledField function

Bug: 1275649
Change-Id: I2bcd25d01ad7dab71ed3c9d2cb0d70f1e3991234
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3861970


Commit-Queue: Vidhan Jain <vidhanj@google.com>
Reviewed-by: Christoph Schwering <schwering@google.com>
Cr-Commit-Position: refs/heads/main@{#1040905}