`restore --all` breaks when password is changed

When restoring all databases from a dump into a new local instance, the restore process fails due to `init.edgeql` overwriting the password for the `admin` role. This prevents further database restoration because authentication fails immediately after the password is changed.

This issue makes remote `restore --all` particularly problematic unless authentication is done using a secret key, which is not straightforward with the current setup.

### Steps to Reproduce
1. Create a new Gel instance and restore all databases from a dump:
```sh
gel instance create -I dump_restore2
gel -I dump_restore2 restore --all $WORK_DIR/dump_all
```

Expected output:
```
(successful restore messages)
✅ OK
```

Actual output:
```
[2025-03-31T20:02:50Z ERROR gel_tokio::raw::connection] Connection error: AuthenticationError: authentication failed
gel error: cannot connect to database "main"
Caused by: Connection error: AuthenticationError: authentication failed
❌ FAIL: exit status: 1
```

### Expected Behavior
The restore process should complete without modifying credentials unless explicitly allowed by the user.

### Actual Behavior
- `init.edgeql` contains an `ALTER ROLE admin` statement that changes the password.
- Since authentication credentials are lost, the restore process fails when trying to restore additional databases.

### Discussion
- `dump --all` is intended to include all roles and authentication settings.
- Overwriting passwords during a restore can cause unexpected authentication failures, particularly for multi-step restorations.

### Possible mitigations:
- Provide a warning before restoring that passwords will be changed.
- Allow users to opt out of restoring passwords.
- Implement an `outro.edgeql` script that restores passwords at the end rather than immediately.
- Use `edgeql-parser` to detect credential changes and prompt the user for confirmation.
- Recommend restoring via the admin socket to bypass authentication issues.

Reproduce the failure with `gel instance create -I dump_restore2` and `gel -I dump_restore2 restore --all $WORK_DIR/dump_all`. Start by examining the generated `init.edgeql` and the restore sequence around its `ALTER ROLE admin` statement. Done means restoring all databases completes without an authentication failure, with the chosen credential behavior covered by a reproducible test.

Written by the indexing model from the issue text.