Fix PeriodicReader shutdown to invoke shutdown on exporter#2477

utpilla merged 2 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-rust:mainfrom

cijothomas:cijothomas/periodicreader-shutdownfixcijothomas/opentelemetry-rust:cijothomas/periodicreader-shutdownfixCopy head branch name to clipboard