ddtrace/ext: change error.msg to error.message for UNC

[zarirhamza]

What does this PR do?

Renames the error.msg tag to error.message tag in order to meet the requirements of naming across all tracers.

[pr-commenter]

Benchmarks

Found 0 performance improvements and 0 performance regressions! Performance is the same for 6 cases.

[ajgajg1134]

Given this is a publicly available tag is there any concern that customers may be relying on this value for their monitors / metrics?

[zarirhamza]

Given this is a publicly available tag is there any concern that customers may be relying on this value for their monitors / metrics?

Nope! This is part of the Unified Naming Changes of which customers have been given ample notice to change their setup and changes to the tracer have been approved by the backend.

[ajgajg1134]

Given this is a publicly available tag is there any concern that customers may be relying on this value for their monitors / metrics?

Nope! This is part of the Unified Naming Changes of which customers have been given ample notice to change their setup and changes to the tracer have been approved by the backend.

OH that's what UNC means :P okay!