test(groq): xfail flaky tool choice test (#38365)

Groq's standard integration suite already treats several tool-calling
checks as flaky because provider behavior is inconsistent. The forced
`tool_choice` check now hits the same provider-side `tool_use_failed`
400 on generic prompts, so the Groq-specific suite marks that case as
expected flaky instead of failing scheduled integration runs.

## Changes
- Add a Groq-specific `test_tool_choice` override that retries and
xfails the shared standard test.
- Keep the rest of the Groq tool-calling coverage unchanged, including
the existing xfail/retry behavior for related standard tests.

libs/partners/groq/tests/integration_tests/test_standard.py

@@ -39,6 +39,11 @@ class TestGroq(ChatModelIntegrationTests):
     def test_tool_calling(self, model: BaseChatModel) -> None:
         super().test_tool_calling(model)
 
+    @pytest.mark.xfail(reason="Retry flaky tool choice behavior")
+    @pytest.mark.retry(count=3, delay=1)
+    def test_tool_choice(self, model: BaseChatModel) -> None:
+        super().test_tool_choice(model)
+
     @pytest.mark.xfail(reason="Retry flaky tool calling behavior")
     @pytest.mark.retry(count=3, delay=1)
     async def test_tool_calling_async(self, model: BaseChatModel) -> None: