chore: Fix more failing system tests

PiperOrigin-RevId: 780706966

Author: matthew29tang

tests/system/vertexai/test_prompts.py

@@ -189,5 +189,7 @@ def test_get_prompt_with_function_calling(self):
         assert prompt.tools
 
         # Generate content using the prompt
-        response = prompt.generate_content(contents=prompt.assemble_contents())
+        response = prompt.generate_content(
+            model_name="gemini-1.5-pro-002", contents=prompt.assemble_contents()
+        )
         assert response

tests/system/vertexai/test_tokenization.py

@@ -41,10 +41,6 @@
 
 
 _MODELS = [
-    "gemini-1.0-pro",
-    "gemini-1.5-pro",
-    "gemini-1.5-flash",
-    "gemini-1.5-flash-002",
     "gemini-1.5-pro-002",
 ]
 _CORPUS = [