feat: move jaeger tests to a separate package

[kruskall]

❓ Why is this being changed

jaeger is included in the module graph of downstream clients as an indirect dependency because of usage in otlp package.
(go module pruning doesn't seem to distinguish test files vs regular files 😢 )

APM Server output:

$ go mod why -m github.com/jaegertracing/jaeger
# github.com/jaegertracing/jaeger
github.com/elastic/apm-server/internal/beater/otlp
github.com/elastic/apm-data/input/otlp
github.com/elastic/apm-data/input/otlp.test
github.com/jaegertracing/jaeger/model

Related to elastic/apm-server#14768

🧑‍💻 What is being changed

move jaeger usage to a separate package along with testdata files

✅ How to validate the change

go test ./... to ensure tests are passing

go mod tidy in apm-server to validate the dependency is removed