RFR: 8267095: Miscellaneous cleanups in vm.runtime.defmeth tests [v2]

[Vladimir Ivanov]

>> Does it look better?
>> https://github.com/openjdk/jdk/pull/4008/commits/66cda654f93e30ad1a6b72c29fb83e84c1a7ae58 
> 
> 
> Yes thanks.
> 
> So these tests will now be updated on each release to update the max 
> version?

Yes. (It is desirable, but not strictly required.)

I also thought about other options (either (1) automatically detect 
maximally supported major class file version; or (2) introduce a central 
place in test library to expose the value), but decided to leave it for 
a future enhancement.

Best regards,
Vladimir Ivanov