AntSpec: Improve filter for warning "Archived non-system classes are disabled"

AntSpec: Improve filter for warning "Archived non-system classes are disabled"

In JDK 21, the prefix has changed once again, no longer being a JVM
specifier like "OpenJDK 64-Bit Server VM" or "Java HotSpot(TM) 64-Bit
Server VM" but rather something like "[0.016s][warning][cds]".

Even worse, before J21, the warning appears on stdErr, but in J21+, it
appears on stdOut.

Fixes LTWTests.testJ14LTWWithXML, which started failing on Java 21.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>