Using SSO to sign up for an account bypasses some of the information that needs to be filled out

This issue has been migrated from [#16256](https://github.com/matrix-org/synapse/issues/16256).

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### Description

For example, assuming that the server is set up to require an email address to register in order to avoid spam as much as possible, when I use GitHub OAuth for authorization to sign up for an account, I can sign up for an account without filling in my email address.

### Steps to reproduce

- Set Synapse to have to verify email address to register
- Setting up to allow third-party authorization registration, such as GitHub OAuth
- Sign up for an account using GitHub OAuth without verifying your email address

### Homeserver

Matrix.org can reproduce this situation

### Synapse Version

Synapse 1.91.1

### Installation Method

Debian packages from packages.matrix.org

### Database

IDK

### Workers

I don't know

### Platform

Matrix.org

### Configuration

IDK

### Relevant log output

```shell
IDK
```

### Anything else that would be useful to know?

_No response_