Removing cruft leftover from the deprecation of include+with_items

Also cleaning up integration tests that had checks for the empty item
attribute in certain results.

Fixes #7535

test/integration/roles/test_async/tasks/main.yml

@@ -35,7 +35,6 @@
         - "'end' in async_result"
         - "'finished' in async_result"
         - "'invocation' in async_result"
-        - "'item' in async_result"
         - "'rc' in async_result"
         - "'start' in async_result"
         - "'stderr' in async_result"