qemu.tests.multi_disk_random_hotplug: Use all 5 monitors

Use 5 monitors in parallel test variant.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

qemu/tests/cfg/multi_disk_random_hotplug.cfg

@@ -34,7 +34,7 @@
         - @serial:
         - parallel:
             multi_disk_type = parallel
-            monitors += " TestHMP1"
+            monitors += " TestHMP1 TestHMP2 TestQMP1 TestQMP2"
             monitor_type_TestHMP1 = human
             monitor_type_TestHMP2 = human
             monitor_type_TestQMP1 = qmp