Element Classic iOS uses non-standard API for redacting event

### Steps to reproduce

Redact an event, I guess?

### Outcome

I am seeing Element iOS users on matrix.org sending `POST /_matrix/client/r0/rooms/{roomId}/redact/{eventId}` requests.

The real standardised endpoint takes an extra `/{txnId}` on the end and seems to have done since r0.1.0: https://spec.matrix.org/legacy/client_server/r0.1.0.html#put-matrix-client-r0-rooms-roomid-redact-eventid-txnid

### Your phone model

_No response_

### Operating system version

_No response_

### Application version

Element Classic/1.11.35 (user-agent string)

### Homeserver

matrix.org

### Will you send logs?

No

Start by reproducing event redaction in Element Classic 1.11.35 and trace the request sent to /_matrix/client/r0/rooms/{roomId}/redact/{eventId}. Compare it with the linked Matrix r0.1.0 endpoint specification; done means redaction uses the standardized endpoint including /{txnId}.

Written by the indexing model from the issue text.