Use createTestJvm.

Tested with:
```
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseSerialGC' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseParallelGC' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseG1GC' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseZGC' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseZGC -XX:+ZGenerational' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseShenandoahGC' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC' ==> TOTAL:1 PASS:1
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:CompressedClassSpaceSize=1g -XX:-UseCompressedClassPointers' ==> TOTAL:0
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:CompressedClassSpaceSize=1g' ==> TOTAL:0
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:-UseCompressedClassPointers' ==> TOTAL:0
make run-test TEST=open/test/hotspot/jtreg/gc/arguments/TestCompressedClassFlags.java JTREG='RETAIN=all;VERBOSE=all;JAVA_OPTIONS=-XX:+UseCompressedClassPointers' ==> TOTAL:0
```