[omnibox] Remove field trial parameter kDisableResultsCachingRule

This CL cleans up all use of kDisableResultsCachingRule and related
logic because it is not in any active experiments.

Bug: 937419
Change-Id: I11543b81e7a3ec68e5a334182a4943d5ce963b0a
Reviewed-on: https://chromium-review.googlesource.com/c/1497224
Reviewed-by: Kevin Bailey <krb@chromium.org>
Commit-Queue: Orin Jaworski <orinj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637007}
4 files changed