Specifying a GC on the command line leads to:

$ make run-test-only JTREG="VM_OPTIONS=-XX:+UseG1GC" TEST="jdk/jfr/event/runtime/TestVMInfoEvent.java"
...
ACTION: main -- Failed. Unexpected exit from test [exit code: 1]
REASON: User specified action: run main/othervm -XX:Flags=TestVMInfoEvent.flags -Xmx500m jdk.jfr.event.runtime.TestVMInfoEvent arg1 arg2
TIME: 0.028 seconds
messages:
command: main -XX:Flags=TestVMInfoEvent.flags -Xmx500m jdk.jfr.event.runtime.TestVMInfoEvent arg1 arg2
reason: User specified action: run main/othervm -XX:Flags=TestVMInfoEvent.flags -Xmx500m jdk.jfr.event.runtime.TestVMInfoEvent arg1 arg2
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jfr,java.management
elapsed time (seconds): 0.028
configuration:
Boot Layer
  add modules: jdk.jfr java.management

STDOUT:
Error occurred during initialization of VM
Multiple garbage collectors selected