Remove enum for actions

It doesn't make sense to have the action schema in a separate file now
that only the `type` is shared.

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

data/schemas/oauth2-account-management-action.yaml

@@ -1,22 +0,0 @@
-# Copyright 2026 The Matrix.org Foundation C.I.C.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-type: string
-enum:
-  - "org.matrix.profile"
-  - "org.matrix.devices_list"
-  - "org.matrix.device_view"
-  - "org.matrix.device_delete"
-  - "org.matrix.account_deactivate"
-  - "org.matrix.cross_signing_reset"
-description: An action that the account management URL supports.

data/schemas/oauth2-account-management-server-metadata.yaml

@@ -26,4 +26,5 @@ properties:
       List of [actions](/client-server-api/#account-management-url-actions) that the account
       management URL supports.
     items:
-      $ref: ./oauth2-account-management-action.yaml
+      type: string
+      description: An action that the account management URL supports.

data/schemas/oauth2-account-management-url.yaml

@@ -15,7 +15,7 @@ type: object
 title: OAuth 2.0 Account Management URL Query Parameters
 properties:
   action:
-    $ref: ./oauth2-account-management-action.yaml
+    type: string
     description: |-
       The action that the user wishes to take. Must match one of the actions advertised by the
       server in [`account_management_actions_supported`](/client-server-api/#account-management-url-discovery).