[NET-9468, NET-9901] Use /v1/exported-services instead of config entry list for exportedServices func

[nathancoleman]

The /v1/config/exported-services endpoint (docs) -- which is currently used for the exportedServices func -- simply returns the config entries as they exist. This means that a wildcarded export, for example, will simply return the wildcard.

In contrast, the /v1/exported-services endpoint (docs) -- introduced in hashicorp/consul#20015 -- resolves wildcards to the resulting list of exported service names and resolves sameness groups to the resulting list of peers and partitions.

With this change, wildcard exports are now expanded out to the full list of exported services instead of just * for the service name:

$ consul-template -template "exported_services.tmpl:out.txt" -once && cat out.txt

source exported from partition default to partitions [other]
destination exported from partition other to partitions [default]
destination2 exported from partition other to partitions [default]
destination3 exported from partition other to partitions [default]

Note

This change means that users must be on Consul 1.17.3+ in order to use the exportedServices function (docs)