User created on user management does not trigger postConfirmation function

### Before opening, please confirm:

- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-adminui/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-adminui/blob/main/CONTRIBUTING.md#bug-reports).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.
- [X] I have removed any sensitive information from my code snippets and submission.

### App Id

d2vmwzre996tav

### Region

us-east-1

### Environment name

dev

### Figma File Version (if applicable)

_No response_

### Amplify CLI Version

10.8.0

### If applicable, what version of Node.js are you using?

_No response_

### What operating system are you using?

_No response_

### Browser type?

chrome

### Describe the bug

When creating a user in the user management page, then confirming the user in the application using hosted UI the postConfirmation function never triggers. But when creating a user on the hosted UI and confirming the user triggers the function for the same application.

https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-identity-pools-working-with-aws-lambda-triggers.html

is there a difference in how studio creates a user?

### Expected behavior

Have consisted behaviour in user creation

### Reproduction steps

1. Create a app with withAuthenticator
2. create a user pool and add postConfirmation function using CLI
3. create a user on Studio and confirm on the application
4. create a user using the hosted UI
5. observe the behaviour is different

### Project Identifier

_No response_

### Additional information

_No response_

Reproduce the issue using the listed Studio and hosted UI steps, then compare how each flow creates and confirms a user. Read the linked Cognito Lambda triggers documentation first; done means the postConfirmation function fires consistently for users created through both flows.

Written by the indexing model from the issue text.