Python: remove mistaken on_activate func (#9839)

### Motivation and Context

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Removes an outdated function `on_activate` from the KernelProcessStep
class and the one place it was overridden.

Fixes #9829 

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

Co-authored-by: Evan Mattson <[email protected]>

python/samples/getting_started_with_processes/step01/step01_processes.py

@@ -37,7 +37,7 @@ class UserInputState(KernelBaseModel):
     current_input_index: int = 0
 
 
-class ScriptedUserInputStep(KernelProcessStep[UserInputState]):
+class UserInputStep(KernelProcessStep[UserInputState]):
     GET_USER_INPUT: ClassVar[str] = "get_user_input"
 
     def create_default_state(self) -> "UserInputState":
@@ -48,26 +48,21 @@ def populate_user_inputs(self):
         """Method to be overridden by the user to populate with custom user messages."""
         pass
 
-    async def on_activate(self):
-        """This is called during the activation of the process step."""
-        self.populate_user_inputs()
-
     async def activate(self, state: KernelProcessStepState[UserInputState]):
         """Activates the step and sets the state."""
         state.state = state.state or self.create_default_state()
         self.state = state.state
         self.populate_user_inputs()
-        pass
 
     @kernel_function(name=GET_USER_INPUT)
     async def get_user_input(self, context: KernelProcessStepContext):
         """Gets the user input."""
         if not self.state:
             raise ValueError("State has not been initialized")
 
-        user_message = self.state.user_inputs[self.state.current_input_index]
+        user_message = input("USER: ")
 
-        print(f"USER: {user_message}")
+        # print(f"USER: {user_message}")
 
         if "exit" in user_message:
             await context.emit_event(process_event=ChatBotEvents.Exit, data=None)
@@ -79,7 +74,7 @@ async def get_user_input(self, context: KernelProcessStepContext):
         await context.emit_event(process_event=CommonEvents.UserInputReceived, data=user_message)
 
 
-class ChatUserInputStep(ScriptedUserInputStep):
+class ScriptedInputStep(UserInputStep):
     def populate_user_inputs(self):
         """Override the method to populate user inputs for the chat step."""
         if self.state is not None:
@@ -89,6 +84,25 @@ def populate_user_inputs(self):
             self.state.user_inputs.append("How wide is the widest river?")
             self.state.user_inputs.append("exit")
 
+    @kernel_function
+    async def get_user_input(self, context: KernelProcessStepContext):
+        """Gets the user input."""
+        if not self.state:
+            raise ValueError("State has not been initialized")
+
+        user_message = self.state.user_inputs[self.state.current_input_index]
+
+        print(f"USER: {user_message}")
+
+        if "exit" in user_message:
+            await context.emit_event(process_event=ChatBotEvents.Exit, data=None)
+            return
+
+        self.state.current_input_index += 1
+
+        # Emit the user input event
+        await context.emit_event(process_event=CommonEvents.UserInputReceived, data=user_message)
+
 
 class IntroStep(KernelProcessStep):
     @kernel_function
@@ -146,14 +160,14 @@ async def get_chat_response(self, context: "KernelProcessStepContext", user_mess
 kernel = Kernel()
 
 
-async def step01_processes():
+async def step01_processes(scripted: bool = True):
     kernel.add_service(OpenAIChatCompletion(service_id="default"))
 
     process = ProcessBuilder(name="ChatBot")
 
     # Define the steps on the process builder based on their types, not concrete objects
     intro_step = process.add_step(IntroStep)
-    user_input_step = process.add_step(ChatUserInputStep)
+    user_input_step = process.add_step(ScriptedInputStep if scripted else UserInputStep)
     response_step = process.add_step(ChatBotResponseStep)
 
     # Define the input event that starts the process and where to send it
@@ -186,4 +200,5 @@ async def step01_processes():
 
 
 if __name__ == "__main__":
-    asyncio.run(step01_processes())
+    # if you want to run this sample with your won input, set the below parameter to False
+    asyncio.run(step01_processes(scripted=False))

python/semantic_kernel/processes/kernel_process/kernel_process_step.py

@@ -21,7 +21,3 @@ class KernelProcessStep(ABC, KernelBaseModel, Generic[TState]):
     async def activate(self, state: "KernelProcessStepState[TState]"):
         """Activates the step and sets the state."""
         pass  # pragma: no cover
-
-    async def on_activate(self):
-        """To be overridden by subclasses if needed."""
-        pass  # pragma: no cover