fix: Update BatchUploader to include integration attributes on AST Background Events

[alexs-mparticle]

Update BatchUploader to include integration attributes and cust…om flags in AST events

Instructions

1. PR target branch should be against development
2. PR title name should follow this format: https://github.com/mParticle/mparticle-workflows/blob/main/.github/workflows/pr-title-check.yml
3. PR branch prefix should follow this format: https://github.com/mParticle/mparticle-workflows/blob/main/.github/workflows/pr-branch-check-name.yml

Summary

• {provide a thorough description of the changes}

Testing Plan

• Was this tested locally? If not, explain why.
• {explain how this has been tested, and what, if any, additional testing should be done}

Reference Issue (For mParticle employees only. Ignore if you are an outside contributor)

• Closes https://go.mparticle.com/work/REPLACEME

[sonarqubecloud]

Quality Gate failed

Failed conditions
55.1% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[mparticle-automation]

🎉 This PR is included in version 2.43.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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