Opening ES to outside hosts should not be the default

[YetAnotherGerrit]

https://docs.zammad.org/en/pre-release/install/elasticsearch/install-elasticsearch-9.html#configuration

This says, that network.host and transport.host should be set to 0.0.0.0, which allows connections to ES from other than localhost. This is not needed for most installations. We should either remove it from the documentation or mark it as optional and describe what happens when you set these to 0.0.0.0.