[SLS-1697] Update Forwarder to handle inferred spans differently

[hghotra]

What does this PR do?

Update trace forwarder logic to not add tags from Lambda function to inferred spans that belong to an external managed service such as SQS, SNS, etc.

Motivation

https://datadoghq.atlassian.net/browse/SLS-1697

The Forwarder fetches Lambda tags and adds them to the span metadata, but this is not accurate for inferred spans because they do not belong to the AWS Lambda service.

Testing Guidelines

• added end to end python unit test
• added go unit test for the trace forwarder

python3 -m unittest discover .
go test -v ../...
./tools/integration_tests/integration_tests.sh

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)
• This PR passes the unit tests
• This PR passes the installation tests (ask a Datadog member to run the tests)

[agocs]

Does it make sense to give aws/logs_monitoring/tests/events/simple.json a more descriptive name?
Otherwise, LGTM

[hghotra]

Does it make sense to give aws/logs_monitoring/tests/events/simple.json a more descriptive name? Otherwise, LGTM

It does, it should be aws_logs.json or cloudwatch_logs.json? Which one do you prefer?

[agocs]

I think I'd be perfectly happy with either, but I think cloudwatch_logs.json is more descriptive