Fix VertexAiGeminiChatModelToolCallingIT#functionCallTestInferredOpenApiSchemaStream

 - Improve user message for the consistent test result assertion Signed-off-by: Ilayaperumal Gopinathan <ilayaperumal.gopinathan@broadcom.com>

Author: ilayaperumalg

models/spring-ai-vertex-ai-gemini/src/test/java/org/springframework/ai/vertexai/gemini/tool/VertexAiGeminiChatModelToolCallingIT.java

@@ -141,7 +141,8 @@ public void functionCallTestInferredOpenApiSchema() {
 public void functionCallTestInferredOpenApiSchemaStream() {
 
 UserMessage userMessage = new UserMessage(
-"What's the weather like in San Francisco, Paris and in Tokyo? Return the temperature in Celsius.");
+"What's the weather like in San Francisco, Paris and in Tokyo? Return the temperature in Celsius."
++ "You must call the getCurrentWeather tool once for each city and return the temperatures in Celsius as plain numbers.");
 
 List<Message> messages = new ArrayList<>(List.of(userMessage));