Can't re-activate account when local passwords disabled and LDAP/SSO enabled

### Description

This is a continuation of : https://github.com/matrix-org/synapse/issues/8393

But also in my case it's specifically LDAP (currently) not SSO

### Steps to reproduce

"Deleted" account (actually disabled it) and cannot re-activate as need to set password, but cannot because all authentication is external (LDAP/SSO) and Matrix has no authority to set user passwords.

### Homeserver

Synapse self-hosted

### Synapse Version

{"server_version":"1.137.0"}

### Installation Method

Docker (matrixdotorg/synapse)

### Database

PostgreSQL

### Workers

Single process

### Platform

Kubernetes

### Configuration

```yaml
password_config:
enabled: true
localdb_enabled: false
modules:
- module: "ldap_auth_provider.LdapAuthProviderModule"
database:
name: psycopg2
```

ZERO federation, fully private

### Relevant log output

```shell
typical log saying not allowed to change password
```

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

This issue has been known and forgotten about for years