RFR(S): 8180631: [TESTBUG] CDS tests should use CDSTestUtils.executeAndLog whenever spawning sub processes

[Mikhailo Seledtsov]

Please review this simple change that uses CDSTestUtils.executeAndLog() 
for starting child
processes in CDS tests, in places that did not use this method before. 
In short, this change brings
benefits of recording the output of child processes thus aiding in 
troubleshooting of failures.
For more details see bug description.

     JBS: https://bugs.openjdk.java.net/browse/JDK-8180631/
     Webrev: http://cr.openjdk.java.net/~mseledtsov/8180631.01/
     Testing:
         CDS tests on Linux-x64 (local) - PASS
         CDS tests via automated multi-platform test system - in Progress

Thank you,
Misha