dbus-display-test is flakey

[Cole Robinson]

Hi Marc-André,

dbus-display-test seems flakey. I'm occasionally seeing:

▶ 692/746
ERROR:../tests/qtest/dbus-display-test.c:68:test_dbus_display_vm:
assertion failed
(qemu_dbus_display1_vm_get_name(QEMU_DBUS_DISPLAY1_VM(vm)) ==
"dbus-test"): (NULL == "dbus-test") ERROR

Examples:

fedora rawhide x86_64:
https://kojipkgs.fedoraproject.org//work/tasks/4945/87834945/build.log
fedora rawhide aarch64:
https://kojipkgs.fedoraproject.org//work/tasks/4946/87834946/build.log
fedora 35 x86_64:
https://download.copr.fedorainfracloud.org/results/@virtmaint-sig/virt-preview/fedora-35-x86_64/04491978-qemu/builder-live.log.gz

This is qemu v7.0.0 with some unrelated patches on top. /usr/bin/make -O
-j5 V=1 VERBOSE=1 check

Side question: I know I can patch meson.build to skip the test, or
similar patch changes, but is there a non-patch way to skip specific tests?

Thanks,
Cole