Remove strict tool invocation config

Author: rpanackal

sample-code/spring-app/src/main/java/com/sap/ai/sdk/app/services/OpenAiService.java

@@ -151,8 +151,7 @@ public OpenAiChatCompletionOutput chatCompletionToolExecution(
     final var request =
         new OpenAiChatCompletionParameters()
             .addMessages(messages.toArray(OpenAiChatMessage[]::new))
-            .setTools(List.of(tool))
-            .setToolChoiceFunction("weather");
+            .setTools(List.of(tool));
 
     final var client = OpenAiClient.forModel(GPT_4O_MINI);
     final var initialResponse = client.chatCompletion(request);