This PR is a first of many that enriches service source to service overrides. In particalar the PR contains:
- introduction of `instrumentation.ServiceNameWithSource` method to be used by all integrations
- 4 integrations covered: grpc, gin-gonic, go-redis, database/sql
- inheritence of service source
- coverage of service mapping configuration
- encoding of source in span.Meta

See other similar PRs in dd-trace-java [PR1 - integration services](DataDog/dd-trace-java#10607),  [PR2- client stats](DataDog/dd-trace-java#10653), [PR3 - config cases](DataDog/dd-trace-java#10658),  [PR4 - manual source](DataDog/dd-trace-java#10704)

<img width="1027" height="655" alt="Screenshot 2026-03-10 at 11 48 36" src="https://github.com/user-attachments/assets/a7db0a35-34cd-4541-bf23-1c8d500af032" />



### Reviewer's Checklist
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- [ ] Changed code has unit tests for its functionality at or near 100% coverage.
- [ ] [System-Tests](https://github.com/DataDog/system-tests/) covering this feature have been added and enabled with the va.b.c-dev version tag.
- [ ] There is a benchmark for any new code, or changes to existing code.
- [ ] If this interacts with the agent in a new way, a system test has been added.
- [ ] New code is free of linting errors. You can check this by running `make lint` locally.
- [ ] New code doesn't break existing tests. You can check this by running `make test` locally.
- [ ] Add an appropriate team label so this PR gets put in the right place for the release notes.
- [ ] All generated files are up to date. You can check this by running `make generate` locally.
- [ ] Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild. Make sure all nested modules are up to date by running `make fix-modules` locally.

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Co-authored-by: raphael.gavache <raphael.gavache@datadoghq.com>