NXD clone_panel: Remove SSH option completely

The default was switched to HTTP in the previous patch, but let's completely
remove SSH option - we support only HTTP for git fetch/push.

app/views/shared/_clone_panel.html.haml

 - project = project || @project
 
 .git-clone-holder.input-group
-  .input-group-btn
+  -# no ssh clone - only http is supported
+  -#.input-group-btn
     - if allowed_protocols_present?
       .clone-dropdown-btn.btn.btn-static
         %span