Hide HTTPS clone button for non-public projects for CAS users

Additionally, the prompt to set a password is no longer shown for CAS
users.

app/helpers/projects_helper.rb

@@ -400,11 +400,7 @@ def default_clone_label
   end
 
   def default_clone_protocol
-    if allowed_protocols_present?
-      enabled_protocol
-    else
-      extra_default_clone_protocol
-    end
+    extra_default_clone_protocol
   end
 
   def extra_default_clone_protocol

app/views/shared/_clone_panel.html.haml

@@ -2,7 +2,7 @@
 
 .git-clone-holder.js-git-clone-holder.input-group
   .input-group-prepend
-    - if allowed_protocols_present?
+    - if allowed_protocols_present? && project.visibility_level == Gitlab::VisibilityLevel::PUBLIC || (current_user && !current_user.cas_user?)
       .input-group-text.clone-dropdown-btn.btn
         %span.js-clone-dropdown-label
           = enabled_project_button(project, enabled_protocol)
@@ -14,8 +14,9 @@
       %ul.dropdown-menu.dropdown-menu-selectable.clone-options-dropdown
         %li
           = ssh_clone_button(project)
-        %li
-          = http_clone_button(project)
+        - if project.visibility_level == Gitlab::VisibilityLevel::PUBLIC || (current_user && !current_user.cas_user?)
+          %li
+            = http_clone_button(project)
 
   = text_field_tag :project_clone, default_url_to_repo(project), class: "js-select-on-focus form-control", readonly: true, aria: { label: 'Project clone URL' }
   .input-group-append