Add stream options to Gemini LLM for usage tracking (#4466)

* Add stream options to Gemini LLM for usage tracking

* Update Gemini LLM to disable prompt token calculation

---------

Co-authored-by: Timothy Carambat <rambat1010@gmail.com>

server/utils/AiProviders/gemini/index.js

@@ -416,9 +416,12 @@ class GeminiLLM {
         stream: true,
         messages,
         temperature: temperature,
+        stream_options: {
+          include_usage: true,
+        },
       }),
       messages,
-      true
+      false
     );
 
     return measuredStreamRequest;