sytest "Can delete canonical alias" is enforcing "MAY" wording in the spec as mandatory

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Sytest "Can delete canonical alias" checks if the server automatically removes an alias from a `m.room.canonical_alias` event if it is deleted via the `/directory/` API.

However, it is probably wrong to enforce this behaviour in two different ways;

First, the spec talks only about `alt_aliases` being automatically updated, see the [following text](https://spec.matrix.org/v1.1/client-server-api/#get_matrixclientv3roomsroomidaliases);

> Note: Servers **may** choose to update the `alt_aliases` for the `m.room.canonical_alias` state event in the room when an alias is removed. Servers which choose to update the canonical alias event are recommended to, in addition to their other relevant permission checks, delete the alias and return a successful response even if the user does not have permission to update the `m.room.canonical_alias` event.

This does not mention anything about the `alias` part of the state event.

Secondly, this is a **MAY** recommendation, which, in the words of [RFC2119](https://datatracker.ietf.org/doc/html/rfc2119);

> This word, or the adjective "OPTIONAL", mean that an item is truly optional.

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Thus, in my opinion, this sytest shouldn't become a *compliance*-testing complement test, but i'd like some input on this.

Beginne mit dem sytest-Test "Can delete canonical alias" und vergleiche seine Assertion mit dem verlinkten Text der Matrix-Spezifikation und den RFC2119-Richtlinien. Ermittle, ob der Test das optionale MAY-Verhalten als verpflichtend behandelt; abgeschlossen ist die Aufgabe, wenn die Erwartung des Compliance-Tests mit der in der Spezifikation angegebenen Anforderung übereinstimmt.

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