chore: parallelize account and resource cleanup for e2e testing

[alharris-at]

Description of changes

Parallelize cleanup both across all accounts simultaneously, and across all resources of a given type at once. This requires configuring all AWS clients with an explicit account and region (except s3, which is global), so there's a bit of a refactor to pass account and regional info all the way down to client construction.

Because logs are all jumbled up now, I've added an accountIndex to each output per-account. Accounts were already opaque, but this way we can at least correlate errors, etc. within an account.

E.g.

[ACCOUNT 5] Deleting S3 Bucket amplify-e02de3f283b84aa5ab02-integtest-210400-deployment
[ACCOUNT 1] Deleting S3 Bucket amplify-iterativetest1-integtest-210353-deployment
[ACCOUNT 5] Deleting CloudFormation stack amplify-auth22dc3507d274a102-integtest-211220
[ACCOUNT 1] Deleting S3 Bucket amplify-a0b27ac02ef4470ab089-integtest-210407-deployment
[ACCOUNT 1] Deleting App lambdaauthenv(dyknllcal7gvg)
[ACCOUNT 1] Cleanup done!
[ACCOUNT 2] Deleting CloudFormation stack amplify-model2dc3507d2f4f1d0-integtest-211447
[ACCOUNT 3] Deleting CloudFormation stack amplify-simplemodel-devtest-204508
[ACCOUNT 4] Deleting CloudFormation stack amplify-deletekeys-integtest-210345
[ACCOUNT 3] Deleting CloudFormation stack amplify-auth32dc3507d2dee8ae-integtest-211423
[ACCOUNT 2] Deleting S3 Bucket amplify-model2dc3507d2f4f1d0-integtest-211447-deployment
[ACCOUNT 4] Deleting S3 Bucket amplify-deletekeys-integtest-210345-deployment
[ACCOUNT 2] Deleting CloudFormation stack amplify-auth52dc3507d25bcf05-integtest-211316
[ACCOUNT 4] Deleting S3 Bucket amplify-817596ddeff44deb970a-integtest-210330-deployment
[ACCOUNT 4] Deleting CloudFormation stack amplify-removeaddconnection-integtest-210951
[ACCOUNT 5] Deleting S3 Bucket amplify-auth22dc3507d274a102-integtest-211220-deployment
[ACCOUNT 5] Deleting CloudFormation stack amplify-auth42dc3507d267ecf7-integtest-211058

Issue #, if available

N/A

Description of how you validated changes

Ran yarn setup-dev && yarn test, and then manually ran cleanup.

Checklist

• PR description included
• yarn test passes

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.