cmd: shutdown for OTel exporters

[Wondertan]

OTel exporters for both tracing and metrics are not gracefully closed. Even though exporters are running the whole Node runtime, and anyway, once the node stops, they are stopped, we still should gracefully close them to be nice and follow best practices. Also, this will be more relevant with runtime switchabilityfor telemetry

[Wondertan]

This is closed for metrics and not for the traces so reopening

[dougEfresh]

@Wondertan see #1524