monitor_test: avoid concurrent access to boolean gracefulShutdownCallbackTriggered
monitor_test: avoid concurrent access to boolean
gracefulShutdownCallbackTriggered

Signed-off-by: Jed Lejosne <58df768959dd06ee96a0a2c42d6cb59ebc2cc6b8@redhat.com>

stu-gott/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt