Revert "Reset NTP customizations when all settings are reset."

This reverts commit dbf62e535bd17e0d260e692250be4d0620d3e564.

Reason for revert: Crash following
ProfileResetter::ResetNtpCustomizations() call.

Original change's description:
> Reset NTP customizations when all settings are reset.
>
> Bug: 931806
> Change-Id: I89db8c24edfb9a7e1c4c6bf3ac3d0faa68d70ca1
> Reviewed-on: https://chromium-review.googlesource.com/c/1472450
> Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
> Reviewed-by: Balazs Engedy <engedy@chromium.org>
> Reviewed-by: Ramya Nagarajan <ramyan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#636087}

TBR=engedy@chromium.org,gayane@chromium.org,ramyan@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 936830
Change-Id: Ib81b7839c10f6bd7e75b438c2f98b015e866d4a5
Reviewed-on: https://chromium-review.googlesource.com/c/1495749
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636610}