Merge branch 'refactor/remove_u_prefix' into 'master'

Remove '/u' prefix form username from Account page

## What does this MR do?

Removes `/u` prefix for username from Account page

Fixes #23323

See merge request !6872

app/views/profiles/accounts/show.html.haml

@@ -86,11 +86,11 @@
           = f.label :username, "Path", class: "label-light"
           .input-group
             .input-group-addon
-              = "#{root_url}u/"
+              = root_url
             = f.text_field :username, required: true, class: 'form-control'
         .help-block
           Current path:
-          = "#{root_url}u/#{current_user.username}"
+          = "#{root_url}#{current_user.username}"
         .prepend-top-default
           = f.button class: "btn btn-warning", type: "submit" do
             = icon "spinner spin", class: "hidden loading-username"