Remove widgets related to Gerrit

The following needs to be removed:

• gerritReviews (jquery.eclipsefdn.api.js)
• gerritReviewCount (jquery.eclipsefdn.api.js)
• gerritUrl property (jquery.eclipsefdn.api.js)
• gerritUserNotFoundMsg (jquery.eclipsefdn.api.js)
• Page caching functionality for gerrit-incoming and gerrit-outgoing (jquery.eclipsefdn.api.js)
• Remove gerrit_repos in msw and any model that may use it