fix: LLM - Fixed get_tuned_model for the future models that are not text-bison

Also fixed the `_endpoint_name` attribute of tuned models although it's not used.

PiperOrigin-RevId: 551363402

Author: Ark-kun

vertexai/language_models/_language_models.py

@@ -42,21 +42,17 @@ def _get_model_id_from_tuning_model_id(tuning_model_id: str) -> str:
     """Gets the base model ID for the model ID labels used the tuned models.
 
     Args:
-        tuning_model_id: The model ID used in tuning
+        tuning_model_id: The model ID used in tuning. E.g. `text-bison-001`
 
     Returns:
         The publisher model ID
 
     Raises:
         ValueError: If tuning model ID is unsupported
     """
-    if tuning_model_id.startswith("text-bison-"):
-        return tuning_model_id.replace(
-            "text-bison-", "publishers/google/models/text-bison@"
-        )
-    if "/" not in tuning_model_id:
-        return "publishers/google/models/" + tuning_model_id
-    return tuning_model_id
+    model_name, _, version = tuning_model_id.rpartition("-")
+    # "publishers/google/models/text-bison@001"
+    return f"publishers/google/models/{model_name}@{version}"
 
 
 class _LanguageModel(_model_garden_models._ModelGardenModel):
@@ -203,6 +199,7 @@ def tune_model(
         tuned_model = job.result()
         # The UXR study attendees preferred to tune model in place
         self._endpoint = tuned_model._endpoint
+        self._endpoint_name = tuned_model._endpoint_name
 
 
 @dataclasses.dataclass