Remove Archival Collections at Institution Header

Description: Remove the “Archival Collections at Institution” header. The search box should sit flush with the remade top banner. Use the “Repositories” link as the link provided on the homepage with a “Browse by Repository” button as detailed in the Home Page, issue #152.

Documentation (More Info): https://docs.google.com/document/d/1caTL_c-QmnNwQJmGG1bto9atOvxKdiwIeAmoFY37Lfo/edit?usp=sharing