Remove package-info.java from test code

Otherwise we have duplicate package-info.java files which caues some
build systems and IDEs to report a failure.

smack-experimental/src/test/java/org/jivesoftware/smackx/spoiler/package-info.java

@@ -1,20 +0,0 @@
-/**
- *
- * Copyright 2018 Paul Schaub
- *
- * 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.
- */
-/**
- * Smack's API for XEP-0382: Spoiler Messages.
-  */
-package org.jivesoftware.smackx.spoiler;