RFR(M): 8221711: [TESTBUG] create more tests for JFR in container environment

[mikhailo.seledtsov at oracle.com]

Please review this change that adds two more test cases for JFR events 
in the container environment:
   - making sure environment variables are reported correctly inside the 
container
   - host info is reported correctly inside the container

     JBS: https://bugs.openjdk.java.net/browse/JDK-8221711
     Webrev: http://cr.openjdk.java.net/~mseledtsov/8221711.01/
     Testing:
       Ran the affected tests on a single host - PASS
       On multiple host variety - In PROGRESS


Thank you,
Misha