Lb cname

[morga471]

As discussed in PR #7, the data items in the upstream module caused issues with planning. We don't need the heritage records from the aws-dns module either....
digging deeper, it seems we haven't been using cname/alias records. They are different than strict cnames -> https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resource-record-sets-choosing-alias-non-alias.html

the aws module docs have a note: Exactly one of records or alias must be specified: this determines whether it's an alias record.
in my 15s of research, every place we have created lb cnames we used a cname record, and the module for cname records isn't using alias.

There is a minor cost savings from this - alias record queries are not charged -> Route 53 doesn't charge for alias queries to AWS resources. For more information, see [Amazon Route 53 Pricing](https://aws.amazon.com/route53/pricing/).

Additional information regarding comparison of alias and cname records -> https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resource-record-sets-choosing-alias-non-alias.html#resource-record-sets-choosing-alias-non-alias-comparison

[nangu001]

LGTM

[mcgin314]

For what it is worth, in my experience all I've ever done is create the a record.