Allow use of "/" in Metrics Instrument Names, and with a 255 char limit #3431
Description
As per the recent specs change :
- Increase max instrument name length from 63 to 255: Increase metric name maximum length from 63 to 255 characters opentelemetry-specification#3648
- Instrument names can have "/" character: Add "/" to valid characters for instrument names opentelemetry-specification#3684
Then update spec compliance matrix https://github.com/open-telemetry/opentelemetry-specification/blob/main/spec-compliance-matrix.md