FIX: Do not show user tips over composer (#20708)

app/assets/javascripts/discourse/app/lib/user-tips.js

@@ -24,6 +24,7 @@ export function showUserTip(options) {
     hideOnClick: false,
     trigger: "manual",
     theme: "user-tips",
+    zIndex: "",
 
     // It must be interactive to make buttons work.
     interactive: true,
@@ -55,6 +56,8 @@ export function showUserTip(options) {
       </div>`,
 
     onCreate(instance) {
+      instance.popper.classList.add("user-tip");
+
       instance.popper
         .querySelector(".btn-dismiss")
         .addEventListener("click", (event) => {

app/assets/stylesheets/common/base/user-tips.scss

@@ -1,3 +1,7 @@
+.user-tip {
+  z-index: z("composer", "content") - 1;
+}
+
 .user-tip-container {
   min-width: 300px;
   padding: 0.5em;