openapi: Fix DELETE /users/me status 200 response description.

If you look at line number 1121 (new) of commit 14c0a387cf,
I seem to have accidently set the description for a status
200 response to "Bad Request" instead of "Success" which
is what it really is. It's basically an ugly typo (maybe
due to hastily copy-pasting the template).

Signed-off-by: Hemanth V. Alluri <hdrive1999@gmail.com>

zerver/openapi/zulip.yaml

@@ -4404,7 +4404,7 @@ paths:
         Delete the requesting user from the realm.
       responses:
         "200":
-          description: Bad Request
+          description: Success.
           content:
             application/json:
               schema:
@@ -4412,7 +4412,7 @@ paths:
                   - $ref: "#/components/schemas/JsonSuccess"
                   - example: {"msg": "", "result": "success"}
         "400":
-          description: Bad Request
+          description: Bad Request.
           content:
             application/json:
               schema: