Register new region: ap-southeast-4

[SankyRed]

🚀 Checklist:

• Add region in AWS_CDK_METADATA (commented out).
• Add region and zone id in ROUTE_53_BUCKET_WEBSITE_ZONE_IDS.
• Add region and zone id in EBS_ENV_ENDPOINT_HOSTED_ZONE_IDS.
• Add region and account in ELBV2_ACCOUNTS.
• Add region and account in DLC_REPOSITORY_ACCOUNTS.
• Add region and account in APPMESH_ECR_ACCOUNTS.
• Add region and ARN in CLOUDWATCH_LAMBDA_INSIGHTS_ARNS for 1.0.178.0.
• Add region and CIDR block address in FIREHOSE_CIDR_BLOCKS.
• Add region and ARN in ADOT_LAMBDA_LAYER_JAVA_SDK_ARNS for most recent version in x86_64 and arm64.
• Add region and ARN in ADOT_LAMBDA_LAYER_JAVA_AUTO_INSTRUMENTATION_ARNS for most recent version in x86_64 and arm64.
• Add region and ARN in ADOT_LAMBDA_LAYER_JAVASCRIPT_SDK_ARNS for most recent version in x86_64 and arm64.
• Add region and ARN in ADOT_LAMBDA_LAYER_PYTHON_SDK_ARNS for most recent version in x86_64 and arm64.
• Add region and ARN in ADOT_LAMBDA_LAYER_GENERIC_ARNS for most recent version in x86_64 and arm64.
• Add region in AWS_REGIONS_AND_RULES.
• Run integ tests and update snapshots

[pahud]

closed by #26919

[github-actions]

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