Change calls from collectAll to collectAllSemiFuture

Summary: We are changing `folly::collectAll` to return `SemiFuture` rather than `Future` and this is needed as an interim step. After all calls to `collectAll` are changed to `collectAllSemiFuture`, we'll be renaming it back to `collectAll`.

Reviewed By: yfeldblum

Differential Revision: D8210974

fbshipit-source-id: e4a7464f4a1c3ede157b8377a4df97d943001f60

folly/futures/test/WaitTest.cpp

@@ -39,7 +39,7 @@ TEST(Wait, waitImmediate) {
   vector<Future<Unit>> v_f;
   v_f.push_back(makeFuture());
   v_f.push_back(makeFuture());
-  auto done_v_f = collectAll(v_f).wait().value();
+  auto done_v_f = collectAllSemiFuture(v_f).toUnsafeFuture().wait().value();
   EXPECT_EQ(2, done_v_f.size());
 
   vector<Future<bool>> v_fb;