Touchups on the s2s swagger definitions

Duplicate properties, wrong types, etc.

api/server-server/leaving.yaml

@@ -57,7 +57,6 @@ paths:
             `room version specification`_ for precise event formats. **The response body
             here describes the common event fields in more detail and may be missing other
             required fields for a PDU.**
-          schema:
           schema:
             type: object
             properties:

api/server-server/query.yaml

@@ -128,7 +128,7 @@ paths:
           x-example: "@someone:example.org"
         - in: query
           name: field
-          type: enum
+          type: string
           enum: ['displayname', 'avatar_url']
           description: |-
             The field to query. If specified, the server will only return the given field

api/server-server/user_devices.yaml

@@ -42,7 +42,6 @@ paths:
           description: |-
             The user ID to retrieve devices for. Must be a user local to the
             receiving homeserver.
-          required: true
           x-example: "@alice:example.org"
       responses:
         200:

api/server-server/version.yaml

@@ -27,6 +27,7 @@ paths:
     get:
       summary: Get the implementation name and version of this homeserver.
       description: Get the implementation name and version of this homeserver.
+      operationId: getVersion
       responses:
         200:
           description:

api/server-server/wellknown.yaml

@@ -29,6 +29,7 @@ paths:
         Gets information about the delegated server for server-server communication
         between Matrix homeservers. Servers should follow 30x redirects, carefully
         avoiding redirect loops, and use normal X.509 certificate validation.
+      operationId: getWellKnown
       responses:
         200:
           description: