installer/pkg/config/aws: fix merge
installer/pkg/config/aws: fix merge

It seems that due to all of the rebasing of the cleanup and validation
changes, some fields we not properly merged. These two fields should be
eliminated. The are the last references to
`tectonic_aws_public_endpoints` and `tectonic_aws_private_endpoints` in
the repository.

kalmog/tectonic-installer,derekhiggins/installer,kalmog/tectonic-installer,derekhiggins/installer,kalmog/tectonic-installer