chore(prebuilt): remove support for models that used bind_X (#5958)

Remove support for models w/ `.bind` used to streamline public API +
recommendations
Also cleaning up `typing.py` file as requested :)

libs/prebuilt/tests/test_react_agent.py

@@ -35,7 +35,6 @@ from langgraph.prebuilt.chat_agent_executor import (
     AgentState,
     AgentStatePydantic,
     StateSchemaType,
-    _get_model,
     _validate_chat_history,
 )
 from langgraph.prebuilt.tool_node import (
@@ -304,24 +303,6 @@ def test_model_with_tools(tool_style: str, version: str, include_builtin: bool)
         )
 
 
-def test_support_preconfigured_models_but_not_for_tools() -> None:
-    """Support (at least temporarily) some model pre-configuration.
-
-    This is a temporary workaround to support pre-configured models
-    for things like temperature or api keys (done via .bind).
-
-    We do not want users to pre-bind tools to the models.
-    """
-    model = FakeToolCallingModel()
-
-    @dec_tool
-    def tool1(some_val: int) -> str:
-        """Tool 1 docstring."""
-        return f"Tool 1: {some_val}"
-
-    create_react_agent(model.bind(temperature=3), [tool1])
-
-
 def test__validate_messages():
     # empty input
     _validate_chat_history([])
@@ -1229,30 +1210,6 @@ def test_tool_node_node_interrupt(
     )
 
 
-def test_get_model() -> None:
-    model = FakeToolCallingModel(tool_calls=[])
-    assert _get_model(model) == model
-
-    @dec_tool
-    def some_tool(some_val: int) -> str:
-        """Tool docstring."""
-        return "meow"
-
-    model_with_tools = model.bind_tools([some_tool])
-    assert _get_model(model_with_tools) == model
-
-    seq = model | RunnableLambda(lambda message: message)
-    assert _get_model(seq) == model
-
-    seq_with_tools = model.bind_tools([some_tool]) | RunnableLambda(
-        lambda message: message
-    )
-    assert _get_model(seq_with_tools) == model
-
-    with pytest.raises(TypeError):
-        _get_model(RunnableLambda(lambda message: message))
-
-
 @pytest.mark.parametrize("version", REACT_TOOL_CALL_VERSIONS)
 def test_dynamic_model_basic(version: str) -> None:
     """Test basic dynamic model functionality."""