Fix: startup path for Go order service

[officialasishkumar]

This pull request improves the startup reliability of the order_service by updating the entrypoint.sh script. The script now checks multiple possible locations for the binary and provides clearer error messaging if it is not found.

Enhancements to binary execution and error handling:

• Updated entrypoint.sh to search for the order-service binary in several locations (ORDER_SERVICE_BIN, /order-service, /app/order-service, ./order-service) and execute the first found executable.
• Added an explicit error message and exit code if the binary is not found, improving debugging and deployment transparency.