RFR(S) : 8243429 : use reproducible random in :vmTestbase_nsk_stress

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8243429/webrev.00
> 82 lines changed: 41 ins; 4 del; 37 mod;

Hi all,

could you please review this small patch?
from JBS: 
> this subtask is to use j.t.l.Utils.getRandomInstance() as a random number generator, where applicable, in :vmTestbase_nsk_stress test group and marking the tests which make use of "randomness" with a proper k/w.

testing: : vmTestbase_nsk_stress test group
JBS: https://bugs.openjdk.java.net/browse/JDK-8243429
webrevs:
- code changes: http://cr.openjdk.java.net/~iignatyev//8243429/webrev.00.code
> 58 lines changed: 41 ins; 4 del; 13 mod; 

- adding k/w: http://cr.openjdk.java.net/~iignatyev//8243429/webrev.00.kw
> 11 lines changed: 0 ins; 0 del; 11 mod;

- full: http://cr.openjdk.java.net/~iignatyev//8243429/webrev.00
> 82 lines changed: 41 ins; 4 del; 37 mod;


Thanks,
-- Igor