Update Prometheus Exporter dependencies to use no-protobuf formats (and adds test)#7664

jkwatson merged 3 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-java:mainfrom

zeitlinger:prom-protobuf-fixzeitlinger/opentelemetry-java:prom-protobuf-fixCopy head branch name to clipboard