Convert invalid inputs (None and empty string) to empty string for tracer name

[eddyleelin]

Description

Specification change #1654 requires invalid names to be converted to an empty string, as described in the tracer specification below. Passing None or the empty string "" as the name parameter to trace.get_tracer(name, version) will now return a tracer with an empty string for tracer.instrumentation_info.name. Full details available in the Trace API specifications.

Fixes #1849

How Has This Been Tested?

• The test_invalid_instrumentation_info unit test has been updated to expect an empty string for the given invalid inputs, and the tox -e test-core-sdk tests passed.

Does This PR Require a Contrib Repo Change?

Not that I believe, but I may be wrong.

Checklist:

• Followed the style guidelines of this project
• Unit tests have been updated
• Changelogs have been updated
• Changes in public API reviewed

Hooray for my first PR!

Resolved by commit 69794b5