chore(vim): remove async from the default test

We are now adding lints test that disable async tests that do not use
await in them. I am by far the biggest offender for this and this is one
of the main reasons. Now any test I write will be synchronous by default
until I need it to be async.

site-modules/core/files/vim/snippets/snippets/js/it.snippet

@@ -3,6 +3,6 @@
 # contributor: Ade Attwood <code@adeattwood.co.uk>
 # filetypes: javascript,javascriptreact,typescript,typescriptreact
 # --
-it('${1}', ${2:async}() => {
+it('${1}', () => {
   ${0}
 });