Add Sytest/Complement coverage to scheduled runs (#2962)

This adds Sytest and Complement coverage reporting to the nightly
scheduled CI runs.

Fixes a few API mode related issues as well, since we seemingly never
really ran them with Complement.

Also fixes a bug related to device list changes: When we pass in an
empty `newlyLeftRooms` slice, we got a list of all currently joined
rooms with the corresponding members. When we then got the
`newlyJoinedRooms`, we wouldn't update the `changed` slice, because we
already got the user from the `newlyLeftRooms` query. This is fixed by
simply ignoring empty `newlyLeftRooms`.

clientapi/routing/leaveroom.go

@@ -18,6 +18,7 @@ import (
 	"net/http"
 
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/internal/httputil"
 	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/util"
@@ -44,6 +45,15 @@ func LeaveRoomByID(
 				JSON: jsonerror.LeaveServerNoticeError(),
 			}
 		}
+		switch e := err.(type) {
+		case httputil.InternalAPIError:
+			if e.Message == jsonerror.LeaveServerNoticeError().Error() {
+				return util.JSONResponse{
+					Code: http.StatusForbidden,
+					JSON: jsonerror.LeaveServerNoticeError(),
+				}
+			}
+		}
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
 			JSON: jsonerror.Unknown(err.Error()),