feat: fixes region and aws account to be used for trigger acc test

[marcosuma]

Related to: https://jira.mongodb.org/browse/INTMDB-1010

As part of enabling trigger creation acceptance tests we need to correctly set up the existing tests. With this change we are using the correct aws_region and aws_account_id when using AWS_EVENTBRIDGE during tests and calling our dev endpoint.

Description

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• Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR.
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• This change requires a documentation update
• Documentation fix/enhancement

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• I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• I have added any necessary documentation (if appropriate)
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• If changes include deprecations or removals, I defined an isolated PR with a relevant title as it will be used in the auto-generated changelog.

Further comments

[marcosuma]

Next actions:

1. How to create a function, app and service IDs?
   • They are basically the env variables MONGODB_REALM_APP_ID, MONGODB_REALM_FUNCTION_ID and MONGODB_REALM_SERVICE_ID
2. Enable tests to be executed as part of CI/CD

[github-actions]

Package	Line Rate	Health
github.com/mongodb/terraform-provider-mongodbatlas/mongodbatlas	2%	❌
github.com/mongodb/terraform-provider-mongodbatlas/mongodbatlas/framework/validator	68%	➖
github.com/mongodb/terraform-provider-mongodbatlas/mongodbatlas/util	17%	❌
Summary	3% (272 / 10318)	❌