FIX: in modal should check for body (#22642)

To decide to use flip behavior select-kit will check if it's located inside a modal as a modal will scroll if overflown, however, when locating the select-kit element in the footer or header this is not the case. This commit will deactivate `flip` modifier only when used inside modal body.

app/assets/javascripts/select-kit/addon/components/select-kit.js

@@ -876,7 +876,7 @@ export default Component.extend(
       this.selectKit.onOpen(event);
 
       if (!this.popper) {
-        const inModal = this.element.closest("#discourse-modal");
+        const inModal = this.element.closest("#discourse-modal .modal-body");
         const anchor = document.querySelector(
           `#${this.selectKit.uniqueID}-header`
         );