Minor fixes for tests (#4686)

* Suggested method for correcting integration tests

* Use static atomics for simplicity

This is consistent with the test immediately below.

* Add assertions to some tests, comments to others

This should fix a handful of tests that didn't correctly do their test.

In other places, comments should make it clearer *why* tests are how
they are.

* Be consistent with existing imports

* remove bad test

* nit

* fix compile errrs

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/core/tests/miri_stress.rs

@@ -5,6 +5,9 @@ use std::rc::Rc;
 use dioxus::prelude::*;
 use dioxus_core::{generation, NoOpMutations};
 
+// The tests in this file are intended to be run with Miri, so not all of them contain assertions.
+// If the tests  complete under Miri, they have passed.
+
 /// This test checks that we should release all memory used by the virtualdom when it exits.
 ///
 /// When miri runs, it'll let us know if we leaked or aliased.