Yet more integration test aliases file cleanup (ansible-collections#431)

* More aliases cleanup
* Mark ec2_classic_lb tests unstable
* Add more comments about why tests aren't enabled

This commit was initially merged in https://github.com/ansible-collections/community.aws
See: ansible-collections/community.aws@cb55efa

tests/integration/targets/ec2_vpc_vgw/aliases

@@ -1,4 +1,5 @@
-cloud/aws
-shippable/aws/group2
 # https://github.com/ansible-collections/community.aws/issues/154
 unstable
+
+cloud/aws
+shippable/aws/group2