Replace prepend-left-20 class in graphs

Also removes the prepend-left-20 class
from the common.scss file

app/assets/stylesheets/framework/common.scss

@@ -389,7 +389,6 @@ img.emoji {
   See https://gitlab.com/gitlab-org/gitlab/-/issues/217418 for more details.
 **/
 .prepend-top-20 { margin-top: 20px; }
-.prepend-left-20 { margin-left: 20px; }
 .append-bottom-20 { margin-bottom: 20px; }
 .ml-10 { margin-left: 4.5rem; }
 .inline { display: inline-block; }

app/views/projects/network/show.html.haml

@@ -8,7 +8,7 @@
         = text_field_tag :extended_sha1, @options[:extended_sha1], placeholder: _("Git revision"), class: 'search-input form-control input-mx-250 search-sha'
         = button_tag class: 'btn btn-success' do
           = sprite_icon('search')
-        .inline.prepend-left-20
+        .inline.gl-ml-5
           .form-check.light
             = check_box_tag :filter_ref, 1, @options[:filter_ref], class: 'form-check-input'
             = label_tag :filter_ref, class: 'form-check-label' do