Enhance Synthetic Span Service Representation

[zarirhamza]

What does this PR do?

Rollout of span naming changes to align serverless product with tracer to create streamlined Service Representation for Serverless

Key Changes:

• Change service name to match instance name for all managed services (aws.lambda -> lambda name, etc) (breaking)

• Add span.kind:server on synthetic spans made via span-inferrer

• Implement DD_TRACE_REMOVE_INTEGRATION_SERVICE_NAMES_ENABLED (default true) to allow users to opt out

Motivation

Improve Service Map for Serverless. This allows for synthetic spans to have their own service on the map which connects with the inferred spans from the tracer side.

Testing Guidelines

Unit and Integration tests updated accordingly.

Matching the service name to the instance name essentially removes the need for a base_service tag in some instances due to essentially removing service overrides

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)

[joeyzhao2018]

LGTM