Merge branch '47273-bs4-header-sub-nav-dropdown-active-states' into 'master'

Resolve "Header sub-nav dropdown triggers missing active state on dropdown open"

Closes #47273

See merge request gitlab-org/gitlab-ce!19402

app/assets/stylesheets/framework/gitlab_theme.scss

@@ -35,7 +35,7 @@
         }
 
         &.active > a,
-        &.dropdown.open > a {
+        &.dropdown.show > a {
           color: $color-900;
           background-color: $color-alternate;
         }
@@ -74,7 +74,7 @@
         }
 
         &.active > a,
-        &.dropdown.open > a {
+        &.dropdown.show > a {
           color: $color-900;
           background-color: $color-alternate;