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Some extensions tests had the toolbar redesign disabled by a custom override.
Some of these are testing legacy behavior, but many were just never changed
over. Update
many to remove the custom override, enabling the redesign.

In order to stay targeted, this CL doesn't update behavior expectations
for any tests. That will be done in a followup.

BUG=None

Review-Url: https://codereview.chromium.org/2311533002
Cr-Commit-Position: refs/heads/master@{#417068}