java/beans/XMLDecoder/8028054/Task.java should use the 3-arg Class.forName

The issue comes from https://github.com/openjdk/jdk/pull/9677#issuecomment-1200811357.

If Loom is not supported, two XMLDecoder tests would fail. The issue could be reproduced by zero, for example:

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TEST: java/beans/XMLDecoder/8028054/TestConstructorFinder.java
...
Caused by: java.lang.UnsupportedOperationException: VM does not support continuations
at java.base/jdk.internal.vm.ContinuationSupport.ensureSupported(ContinuationSupport.java:49)
at java.base/jdk.internal.vm.Continuation.<clinit>(Continuation.java:52)
... 9 more
...

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TEST: java/beans/XMLDecoder/8028054/TestMethodFinder.java
...
Caused by: java.lang.UnsupportedOperationException: VM does not support continuations
at java.base/jdk.internal.vm.ContinuationSupport.ensureSupported(ContinuationSupport.java:49)
at java.base/jdk.internal.vm.Continuation.<clinit>(Continuation.java:52)
... 9 more
...
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