RFR 8194086: Remove deprecated experimental flag UseCGroupMemoryLimitForHeap

[harold seigel]

Hi,

Please review this small JDK-11 change to remove deprecated experimental 
option UseCGroupMemoryLimitForHeap.

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8194086/webrev/index.html

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8194086

The change was tested by hand:

     > java -XX:+UseCGroupMemoryLimitForHeap -version
    Unrecognized VM option 'UseCGroupMemoryLimitForHeap'
    Error: Could not create the Java Virtual Machine.
    Error: A fatal exception has occurred. Program will exit.

     > java -XX:-UseCGroupMemoryLimitForHeap -version
    Unrecognized VM option 'UseCGroupMemoryLimitForHeap'
    Error: Could not create the Java Virtual Machine.
    Error: A fatal exception has occurred. Program will exit.

Additionally, JPRT and Mach5 t1 - t5 tests were run to check for any 
tests that might rely on the option.

Thanks, Harold