use ddsaml2aws

[joeyzhao2018]

What does this PR do?

replace saml2aws with ddsaml2aws https://datadoghq.atlassian.net/wiki/spaces/ENG/pages/1842709292/US1-Fed+Access#CLI%2FTerraform-Access

Motivation

Testing Guidelines

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)

[kimi-p]

lgtm ty!