fix: default to not generate ftv1 traces

[dariuszkuc]

Federation tracing should only be enabled if the Router/Gateway sends the proper ftv1 header and value. Currently trace data is generated even if the header is not specified which leads to unnecessary computations of data that will ultimately be discarded by the Router/Gateway.... If header is not specified, we should default to false to avoid those unnecessary computations.

See: https://www.apollographql.com/docs/federation/metrics/

Supersedes: https://github.com/apollographql/federation-jvm/pull/368

[github-actions[bot]]

Apollo Federation Subgraph Compatibility Results

Federation 1 Support	Federation 2 Support
_service 🟢 @key (single) 🟢 @key (multi) 🟢 @key (composite) 🟢 repeatable @key 🟢 @requires 🟢 @provides 🟢 federated tracing 🟢	@link 🟢 @shareable 🟢 @tag 🟢 @override 🟢 @inaccessible 🟢 @composeDirective 🟢 @interfaceObject 🟢

Learn more:

• Apollo Federation Subgraph Specification
• Compatibility Tests