use leaner install of dd-trace and remove hack around it

[rochdev]

What does this PR do?

Use leaner install of dd-trace and remove hack around it.

Motivation

The package size of dd-trace was historically too large for Lambda, so a lot of files are manually removed in the Dockerfile. The latest version is now a lot leaner when optional dependencies are excluded, so this is no longer needed.

Testing Guidelines

Relying on the existing tests in CI.

Additional Notes

The current version of the PR uses the main branch instead of a real version as a release wasn't done with this change yet. I'll update it before getting it out of draft.

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)