Migrate from deprecated LOCALSTACK_API_KEY to LOCALSTACK_AUTH_TOKEN

[HVbajoria]

Summary

This PR migrates all usages of the deprecated LOCALSTACK_API_KEY environment variable to the new LOCALSTACK_AUTH_TOKEN to ensure continued authentication with LocalStack Pro services.

Background

The LOCALSTACK_API_KEY has been sunset and will no longer work for authentication. Without this migration, sample tests will fail due to authentication errors since the API key mechanism is deprecated. FIXES #262

Changes Made

Core Migration

• .github/workflows/makefile.yml: Updated CI workflow to use LOCALSTACK_AUTH_TOKEN instead of LOCALSTACK_API_KEY
• emr-serverless-python-dependencies/docker-compose.yml: Removed deprecated LOCALSTACK_API_KEY environment variable

Documentation Updates

• testcontainers-java-sample/LocalStackTestcontainers/src/test/java/TestRDS.java: Updated variable name from api_key to authToken for consistency
• sample-archive/spring-cloud-function-microservice/.env.example: Updated placeholder format from <your-pro=api-key> to <your-auth-token>
• java-notification-app/README.md: Updated documentation to use <your-auth-token> format
• route53-dns-failover/README.md: Updated documentation to use <your-auth-token> format

Testing Steps

1. Verification of Migration

# Confirmed no LOCALSTACK_API_KEY references remain
grep -r "LOCALSTACK_API_KEY" . --exclude-dir=.git
# Result: No matches found ✅

# Verified LOCALSTACK_AUTH_TOKEN is properly used
grep -r "LOCALSTACK_AUTH_TOKEN" . --exclude-dir=.git | wc -l
# Result: 40+ references found ✅

2. Local Testing

# Set up environment
export LOCALSTACK_AUTH_TOKEN=<auth-token>
pip install localstack[pro] awscli-local

# Test basic functionality
localstack start -d
localstack wait -t 30
awslocal s3 mb s3://test-migration
awslocal s3 ls
localstack stop
# Result: No authentication errors ✅

3. Sample Testing

# Test terraform sample
cd terraform-resources
export LOCALSTACK_AUTH_TOKEN=<auth-token>
make start && make ready && make run && make stop
# Result: Sample completed successfully ✅

# Test serverless sample  
cd serverless-lambda-layers
make test-ci
# Result: Lambda deployment and invocation successful ✅

4. Docker Compose Testing

# Test docker-compose integration
cd java-notification-app
export LOCALSTACK_AUTH_TOKEN=<auth-token>
docker-compose up -d
docker-compose logs localstack | grep -i error
# Result: No authentication errors in logs ✅

5. CI Workflow Validation

• Verified GitHub workflow uses LOCALSTACK_AUTH_TOKEN: ${{ secrets.TEST_LOCALSTACK_AUTH_TOKEN }}
• Confirmed secret name change from TEST_LOCALSTACK_API_KEY to TEST_LOCALSTACK_AUTH_TOKEN

Impact

• ✅ All sample tests will continue to work with LocalStack Pro
• ✅ No breaking changes for users (they just need to use the new environment variable)
• ✅ Consistent authentication mechanism across all samples