[Compare] Reduce app test output and disable animations during testing

This patch reduces unnecessary app test output using NiceMock and
reduces test runtime by disabling the table sliding animations during
testing.

This patch also updates the Compare page to only fetch a user's
available comparison tables when the new management interface is
enabled, as this previously caused some issues with testing when
`getAllProductSpecificationsSets` was called without the method being
mocked.

Change-Id: Iad7a7a39777cd7cf524708557aaeee6b78e5d691
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6170947
Commit-Queue: Chase Hartsell <chazzy@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1406817}