Changed too many changes buttons to white

Closes #13751

app/views/projects/diffs/_warning.html.haml

@@ -3,17 +3,16 @@
     Too many changes to show.
     .pull-right
       - unless diff_hard_limit_enabled?
-        = link_to "Reload with full diff", url_for(params.merge(force_show_diff: true, format: nil)), class: "btn btn-sm btn-warning"
+        = link_to "Reload with full diff", url_for(params.merge(force_show_diff: true, format: nil)), class: "btn btn-sm"
 
       - if current_controller?(:commit) or current_controller?(:merge_requests)
         - if current_controller?(:commit)
-          = link_to "Plain diff", namespace_project_commit_path(@project.namespace, @project, @commit, format: :diff), class: "btn btn-warning btn-sm"
-          = link_to "Email patch", namespace_project_commit_path(@project.namespace, @project, @commit, format: :patch), class: "btn btn-warning btn-sm"
+          = link_to "Plain diff", namespace_project_commit_path(@project.namespace, @project, @commit, format: :diff), class: "btn btn-sm"
+          = link_to "Email patch", namespace_project_commit_path(@project.namespace, @project, @commit, format: :patch), class: "btn btn-sm"
         - elsif @merge_request && @merge_request.persisted?
-          = link_to "Plain diff", merge_request_path(@merge_request, format: :diff), class: "btn btn-warning btn-sm"
-          = link_to "Email patch", merge_request_path(@merge_request, format: :patch), class: "btn btn-warning btn-sm"
+          = link_to "Plain diff", merge_request_path(@merge_request, format: :diff), class: "btn btn-sm"
+          = link_to "Email patch", merge_request_path(@merge_request, format: :patch), class: "btn btn-sm"
   %p
     To preserve performance only
     %strong #{shown_files_count} of #{diffs.size}
     files are displayed.
-