test: revert throw assertion in arrayContainsAnyQueries test

Modified the `arrayContainsAnyQueries` test to reflect updated backend
behaviour.

The throw assertion was added in
#2299.
It seems the backend behaviour has changed and now there is no
excecption thrown.

Author: dlarocque

google-cloud-firestore/src/test/java/com/google/cloud/firestore/it/ITSystemTest.java

@@ -1944,13 +1944,7 @@ public void arrayContainsAnyQueries() throws Exception {
 
     Query query = randomColl.whereArrayContainsAny("array", Arrays.<Object>asList(42, 43));
 
-    if (getFirestoreEdition() == FirestoreEdition.STANDARD) {
-      assertEquals(asList("a", "b", "d", "e"), querySnapshotToIds(query.get().get()));
-    } else {
-      // TODO: Currently rejected because of mixed type setup, backend will change the behavior; and
-      // this test will fail by then.
-      assertThrows(ExecutionException.class, () -> querySnapshotToIds(query.get().get()));
-    }
+    assertEquals(asList("a", "b", "d", "e"), querySnapshotToIds(query.get().get()));
   }
 
   @Test