fix: disable drop_params to preserve streaming metadata in LiteLLM

- Set drop_params: false in litellm_settings
- Set modify_params: false in litellm_settings
- Set drop_params: false in default_litellm_params
- Commented out LITELLM_DROP_PARAMS env var
- Removed --drop_params command flag

These settings were stripping critical streaming parameters causing
vLLM streaming responses to collapse into empty deltas

ai/litellm-config.yaml

@@ -61,7 +61,7 @@ model_list:
       max_parallel_requests: 1
 
 litellm_settings:
-  drop_params: true
+  drop_params: false  # DISABLED: Was breaking streaming
   set_verbose: true  # Enable verbose logging for debugging streaming issues
   # Disable caching - it breaks streaming responses
   cache: false
@@ -73,7 +73,7 @@ litellm_settings:
   # Force strip specific parameters globally
   allowed_fails: 0
   # Modify params before sending to provider
-  modify_params: true
+  modify_params: false  # DISABLED: Was breaking streaming
   # Enable success and failure logging but minimize overhead
   success_callback: []  # Disable all success callbacks to reduce DB writes
   failure_callback: []  # Disable all failure callbacks
@@ -83,7 +83,7 @@ router_settings:
 
 # Drop unsupported parameters
 default_litellm_params:
-  drop_params: true
+  drop_params: false  # DISABLED: Was breaking streaming
 
 general_settings:
   disable_responses_id_security: true