jdk11_tier1_buffer is subset of jdk_nio, which cause 13 duplicated testcases

[sendaoYan]

Describe the bug

jdk11_tier1_buffer in openjdk/playlist.xml

jdk_nio in openjdk/playlist.xml

jdk_nio in jdk11u/test/jdk/TEST.groups:

13 duplicate testcases:

java/nio/Buffer/AllocateDirectInit.java
java/nio/Buffer/Basic.java
java/nio/Buffer/ByteBufferViews.java
java/nio/Buffer/CharAt.java
java/nio/Buffer/Chars.java
java/nio/Buffer/Chew.java
java/nio/Buffer/CopyDirectMemory.java
java/nio/Buffer/DirectBufferAllocTest.java
java/nio/Buffer/EqualsCompareTest.java
java/nio/Buffer/LimitDirectMemory.java
java/nio/Buffer/LimitDirectMemoryNegativeTest.java
java/nio/Buffer/Order.java
java/nio/Buffer/StringCharBufferSliceTest.java

To Reproduce jtreg -l test/jdk/java/nio/Buffer