Also upload the agent artifact to Maven Central. (#547)
Also upload the agent artifact to Maven Central. (#547)

* Also upload the agent artifact to Maven Central.

* opencensus-agent is now opencensus-contrib-agent.

bogdandrutu/instrumentation-java,census-instrumentation/opencensus-java,songy23/instrumentation-java,bogdandrutu/opencensus-java,sebright/instrumentation-java,census-instrumentation/opencensus-java,bogdandrutu/instrumentation-java,songy23/instrumentation-java,sebright/opencensus-java,sebright/opencensus-java,bogdandrutu/opencensus-java,bogdandrutu/opencensus-java,sebright/opencensus-java,census-instrumentation/opencensus-java,sebright/instrumentation-java,songy23/instrumentation-java