Remove duplicated BS display properties from Diff's HAML

Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

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

@@ -7,7 +7,7 @@
 
 .content-block.oneline-block.files-changed.diff-files-changed.js-diff-files-changed
   .files-changed-inner
-    .inline-parallel-buttons.d-none.d-sm-none.d-md-block
+    .inline-parallel-buttons.d-none.d-md-block
       - if !diffs_expanded? && diff_files.any? { |diff_file| diff_file.collapsed? }
         = link_to _('Expand all'), url_for(safe_params.merge(expanded: 1, format: nil)), class: 'btn btn-default'
       - if show_whitespace_toggle

changelogs/unreleased/264790-bs4-optimization-diff.yml

+---
+title: Remove duplicated BS display properties from Diff's HAML
+merge_request: 44848
+author: Takuya Noguchi
+type: other