feat: push layers in batches

[astuyve]

What does this PR do?

Forks up to 60 times to push layers to various regions, which is super helpful in terms of overall release speed

Motivation

The process as it stands today takes hours, now it only takes a few minutes, even backfilling 100 layers to each region

Testing Guidelines

I tested this release process manually multiple times, including in the latest production release for datadog-lambda-js

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)