Describe the bug
We used to mimic the spanmetrics processor to generate metric names in-line with the convention defined for this processor.

However, the processor has now been deprecated in favour of the spanmetrics connector which also changes the convention of the metrics generated.

The full list of breaking changes can be seen here: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/connector/spanmetricsconnector/README.md#span-to-metrics-processor-to-span-to-metrics-connector

To Reproduce
The Intro to MLT repo includes a branch (soon to be merged) that includes the spanmetrics connector via Flow which can be enabled to show the differences. The default dashboards will not work without appropriate changes from _latency_ to _duration_milliseconds_ naming.

Expected behavior
We should probably support the new naming conventions. However, that also potentially breaks customer dashboards in the wild as it would require that any use of the prior metrics naming conventions are now updated. New customers would, of course, expect the new naming convention.

Environment:

• Infrastructure: N/A
• Deployment tool: N/A