Remove unused protocol.

ElementX/Sources/Other/NotificationCenterProtocol.swift

@@ -1,24 +0,0 @@
-//
-// Copyright 2023 New Vector Ltd
-//
-// 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.
-//
-
-import Foundation
-
-// sourcery: AutoMockable
-protocol NotificationCenterProtocol: AnyObject {
-    func post(name aName: NSNotification.Name, object anObject: Any?)
-}
-
-extension NotificationCenter: NotificationCenterProtocol { }