[mv3] Hide list group which have no list

Related discussion:
uBlockOrigin/uBOL-home#713

Author: gorhill

platform/mv3/extension/css/settings.css

@@ -145,6 +145,9 @@ section[data-pane="rulesets"] > div:first-of-type > p:last-of-type {
 .listEntry[data-role="rootnode"] > .detailbar > *:not(.listExpander) {
     pointer-events: none;
     }
+.listEntry[data-role="rootnode"]:has(> .listEntries:empty) {
+    display: none;
+    }
 .listEntry .detailbar .count {
     align-self: flex-end;
     color: var(--ink-3);