tests: remove useless test file

tests/html/await-fetch.html

@@ -1,10 +0,0 @@
-<script>
-  (async function() {
-    const response = await fetch(new Request('https://httpbin.io/json'));
-    if (response.ok) {
-      document.firstElementChild.appendChild(document.createTextNode(response.ok+"\n"));
-      const body = await response.text();
-      document.firstElementChild.appendChild(document.createTextNode("body:"+body+"\n"));
-    }
-  }());
-</script>