on prem changes to disable cloud solutions

[jen-scymanski-scale]

Pull Request Summary

What is this PR changing? Why is this change being made? Any caveats you'd like to highlight? Link any relevant documents, links, or screenshots here if applicable.

Fixes Needed for model-engine to work on-prem
AWS Disable Logic: Added DISABLE_AWS=true environment variable support
Redis Fallback: S3 backend falls back to Redis when AWS is disabled
Lazy Initialization: Celery apps are initialized lazily to avoid import-time AWS sessions
On-Premises Redis: Added direct Redis connection support via ONPREM_REDIS_HOST
Configurable Gunicorn: Made worker timeouts and settings configurable via environment variables
Thread-Safe Logging: Fixed potential race conditions in logger initialization
Broker Disable Options: Added DISABLE_SQS_BROKER and DISABLE_SERVICEBUS_BROKER flags

Test Plan and Usage Guide

How did you validate that your PR works correctly? How do you run or demo the code? Provide enough detail so a reviewer can reasonably reproduce the testing procedure. Paste example command line invocations if applicable.

Tested locally with scripts
AWS Disable Logic: Tested DISABLE_AWS=true prevents AWS session creation
Redis Fallback: Verified S3 backend falls back to Redis when AWS disabled
Lazy Initialization: Confirmed Celery apps don't create AWS sessions at import time
Thread-Safe Logging: Tested logger initialization in multi-threaded environments
Direct Redis Connection: Tested ONPREM_REDIS_HOST configuration
Server Startup: Confirmed server starts with all cloud services disabled
Environment Variables: Verified all new config variables work correctly
Async Task Workflow: Tested complete task submission and result retrieval
Broker Disable Logic: Verified SQS/ServiceBus fallback to Redis
Error Handling: Tested graceful handling of missing AWS credentials
Backward Compatibility: Confirmed existing cloud functionality still works
No Breaking Changes: Verified no existing APIs are broken