feat: Add batchItemFailures metric

[astuyve]

What does this PR do?

Adds the enhanced metric for batch item failures which I apparently missed when we first added it.

Motivation

Helps users track when SQS enabled systems return errors but overall succeed

Testing Guidelines

automated testing is good but we can also manually exercise this

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)