fix: Use constant for service.name from semconv library

[pkanal]

Which problem is this PR solving?

While doing some bundle size analysis, noticed that the @opentelemetry/semantic-conventions library is a significant contributor to the bundle size because it has a lot of unminified constants. There was a PR merged that also exports each constant by itself instead of on an object which allows tree shaking to only import that constant instead of a whole object. This PR uses the new constants from the @opentelemetry/semantic-conventions instead of the deprecated SemanticConventions object.

Short description of the changes

• Use exported constant for service name.

How to verify that this has the expected result

• Smoke tests pass
• Service name is still respected, run the example app locally and check that service name is set to the value expected.

[MustafaHaddara]

confirmed the new name lines up with the old name: