[vector] Fix jmh build failure about SumOfUnsignedBytes.java

The following java file will result in jmh build faiilure.
test/jdk/jdk/incubator/vector/benchmark/src/main/java/benchmark/jdk/incubator/vector/SumOfUnsignedBytes.java

The reason is as follows:
SumOfUnsignedBytes.java uses some old APIs which have been removed. These APIs are removed in commit http://hg.openjdk.java.net/panama/dev/rev/3b869865b8ed. Updated the test case to use alternative Vector APIs.