Remove HAML tabs from profile

The following discussion from !140054 (merged) should be addressed:

• @leipert started a discussion: (+3 comments)

  @peterhegman I wasn't a 100% sure whether we can remove the tabs rendered below.

  I tried out :profile_tabs_vue but it didn't seem feature complete.

  I really didn't want to touch this because the goal of this MR was to get rid of the show_super_sidebar? helper. WDYT of a follow-up for simplifying the user profile code?

Proposal

Now that the sidebar is permanent we don't need to support the HAML tabs on the profile. Instead we should be able to just render the correct content based on what navigation item is selected.

Note: we are currently in the process of moving this page to Vue but it won't be completed for a little bit. We should leave the #js-profile-tabs mount element in the HAML file but don't need to worry too much about how it looks. See &9056 for more detail.

Implementation guide

1. Move data attributes on each tab in app/views/users/show.html.haml#L117 to the navigation items in the sidebar.
2. Remove tab navigation in app/views/users/show.html.haml#L117
3. Change event listener in app/assets/javascripts/pages/users/user_tabs.js#L106 to listen to the sidebar nav item clicks.