Don't set timeout when showing CDM UI

Since it's a UI-based operation, there's no need to set a timeout.

Test: manual; atest CompanionDeviceManagerTest
Change-Id: I3c399858064eefc1eaa867201551f1652198cb06

services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java

@@ -317,7 +317,7 @@ public class CompanionDeviceManagerService extends SystemService implements Bind
                     AndroidFuture<Association> future = new AndroidFuture<>();
                     service.startDiscovery(request, callingPackage, callback, future);
                     return future;
-                }).whenComplete(uncheckExceptions((association, err) -> {
+                }).cancelTimeout().whenComplete(uncheckExceptions((association, err) -> {
                     if (err == null) {
                         addAssociation(association);
                     } else {