fix(dynamic-booking): respect username order when picking the conferencing app (#30124)

The first member of a dynamic group decides which conferencing app the group
booking uses. getPublicEvent read users[0] straight from findUsersByUsername,
which does not guarantee the order given in the URL, so /alice+bob could end up
using bob's preference — or fall back to Cal Video when only alice has one set.

handleNewBooking already sorts by the dynamic user list for this exact reason
(sortUsersByDynamicList in getLocationValuesForDb.ts). Applying the same order
here keeps the advertised location and the booked location in sync.

packages/features/eventtypes/lib/getPublicEvent.ts

@@ -299,7 +299,15 @@ export const getPublicEvent = async (
       usernameList,
       orgSlug: org,
     });
-    const users = usersInOrgContext;
+    // The first member of a dynamic group decides which conferencing app is used, so the order
+    // given in the URL has to win here. findUsersByUsername does not guarantee that order, which
+    // means /alice+bob could pick bob's preference. handleNewBooking already sorts for exactly
+    // this reason (sortUsersByDynamicList in getLocationValuesForDb.ts) — without the same sort
+    // here, the booking page can advertise a different location than the one actually booked.
+    const users = [...usersInOrgContext].sort(
+      (a, b) =>
+        usernameList.indexOf(a.username ?? "") - usernameList.indexOf(b.username ?? "")
+    );
 
     const defaultEvent = getDefaultEvent(eventSlug);
     let locations = defaultEvent.locations ? (defaultEvent.locations as LocationObject[]) : [];