Replace ArcIntentHelperBridge with FakeIntentHelperHost where possible

There is no reason for those tests to use the real intent_helper.mojom
implementation since they are not for testing intent_helper.mojom
itself. For them, we can instead use FakeIntentHelperHost which is
much simpler.

BUG=None

Change-Id: Id649d9608a92090688c462c432c24e3abfd8e4da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3385625


Reviewed-by: Yury Khmel <khmel@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#959483}