Redacting an `m.space.child` / `parent` event does not remove a room from a space

### Steps to reproduce

Redacting a state event means that the content of that event is now more-or-less empty (membership events are a notable special-case). That means that if someone redacts an an `m.space.child` / `parent` event, the relevant child is no longer a member of the parent space.

But according to https://github.com/matrix-org/matrix-spec/issues/2252:

> Element Web doesn't support this and expects empty m.space.child/parent events to be sent instead.

### Outcome

#### What did you expect?

#### What happened instead?

### Operating system

_No response_

### Browser information

_No response_

### URL for webapp

_No response_

### Application version

_No response_

### Homeserver

_No response_

### Will you send logs?

Yes