The defer block support introduces a new asynchronous form of the set class metadata Angular function. This form
is needed to allow for providing metadata for dynamically imported deferred components. The asynchronous compileComponents
call within TestBed is now used to initialize this metadata during unit tests. Unit tests that contain defer blocks
must use this call prior to executing a test to allow templates containing defer to properly render. Existing tests that
do not use the new defer block do not require modification unless the defer block is introduced into components used in
the unit test.
`compileComponents` is not necessary when using the CLI (as the templates are inlined) and just adds boilerplate code. So we can remove it from the test schematic and make it independent from `async/await` (only place we would have it in the CLI generated code, and in most Angular apps).
