Investigate highlight failure in a few Find Toolbar tests

[tracywalker]

navigate_quick_find, navigate_search_links_only_results, search_link_only and search_quick_find are failing because items are not highlighted as expected. This is either a Firefox bug or a change in Firefox behavior that isn't correctly reflected in the TestRail test cases.

Until we figure out what is going on, please disable the above four test cases with

blocked_by={'id': 'issue_1628', 'platform': OSPlatform:ALL}