RFR (xs) 8251209 [TESTBUG] CDS jvmti tests should use "@modules java.instrument"

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8251209
http://cr.openjdk.java.net/~iklam/jdk16/8251209-cds-jvmti-tests-modules-tag.v01/

Summary -- changed the tests from (mis)using

  * @requires vm.flavor != "minimal"

to

  * @modules java.instrument

... to be consistent with other jvmti tests.

Thanks
- Ioi