[FFI/Jtreg]Exclude VaListTest in JDK20 (#4489)

The change exclude this test suite as we no longer
need VaList as specified in the latest JEP442 at
eclipse-openj9/openj9#16951

Fixes: eclipse-openj9/openj9/issues/17091

Signed-off-by: ChengJin01 <jincheng@ca.ibm.com>

openjdk/excludes/ProblemList_openjdk20-openj9.txt

@@ -484,6 +484,7 @@ java/foreign/TestIllegalLink.java https://github.com/eclipse-openj9/openj9/issue
 java/foreign/TestUnsupportedPlatform.java https://github.com/eclipse-openj9/openj9/issues/14828 generic-all
 java/foreign/TestHandshake.java https://github.com/eclipse-openj9/openj9/issues/13211 generic-all
 java/foreign/StdLibTest.java https://github.com/eclipse-openj9/openj9/issues/16386 aix-ppc64
+java/foreign/valist/VaListTest.java https://github.com/adoptium/aqa-tests/issues/1297 generic-all
 
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