[Documentation] EC2 Guide - change in script paths for example configurations

Due to JBEAP-12047, the configuration scripts that are mentioned in the documentation won't result in a started and configured EAP. We'll need to switch some paths to refer to a different set of configuration files. The examples that are currently referenced will have to go away anyway, since they duplicate those that we normally ship with EAP. See JBEAP-12047 for details.

For standalone configuration files, we'll need to scan the EC2 book for paths that begin with /etc/opt/rh/eap7/jboss-ec2-eap/standalone (both links to standalone-ec2-ha.xml and standalone-mod_cluster-ec2-ha.xml) and change those to refer to the file /opt/rh/eap7/root/usr/share/wildfly/docs/examples/configs/standalone-ec2-ha.xml. Some wording changes may be necessary.

For domain configuration files, there are unfortunately no domain-ec2 examples in the docs/examples/configs directory. We are currently left without a working alternative here. Customers will still be able to produce a working config (and it shouldn't be too hard), but it won't be as easy as it could be. Maybe this could be mentioned somewhere?

The paths for domain example configs will still have to change at some point in the future.