[OsSettingsLanguages] Update cr-action-menu focus background to 6% black

http://crbug/1107917 update cr-action-menu focus background-color
across webui. UX is considering having different behavior between hover
and focus. For now keep this color to be consistent with other menus.

Bug: 1113439
Change-Id: Idf5847f877b234ba082cc4c353082018a0328fec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2438343Reviewed-by: Regan Hsu <hsuregan@chromium.org>
Commit-Queue: My Nguyen <myy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812000}

chrome/browser/resources/settings/chromeos/os_languages_page/os_languages_page_v2.html

@@ -36,6 +36,10 @@
         min-height: 36px;
       }
 
+      cr-action-menu.complex .dropdown-item:focus {
+        background-color: var(--cros-menu-item-bg-color-focus);
+      }
+
       cr-policy-indicator {
         margin-inline-end: 8px;
       }