restore original Alibaba copyright line in two files

test/jdk/jdk/jfr/event/gc/detailed/TestGCLockerEvent.java

was modified by the following fix:

JDK-8260524: validate-source fails on test/jdk/jdk/jfr/event/gc/detailed/TestGCLockerEvent.java

test/jdk/jdk/jfr/api/consumer/TestChunkInputStreamAvailable.java

was modified by the following fix:

JDK-8261157: Incorrect GPL header after JDK-8259956

In both JDK-8260524 and JDK-8261157, the original Alibaba
copyright line was changed:

- * Copyright (c) 2021, Alibaba Group Holding Limited. All Rights Reserved.
+ * Copyright (c) 2021, Alibaba Group Holding Limited. All rights reserved.

and that should not have happened.