bug#32084: dbus-tests try to open X11 connection

[Glenn Morris]

Package: emacs
Severity: minor
Version: 27.0.50

I connect via ssh to a RHEL7 system where I have a local graphical
session running. In current master, running

make -C test lisp/net/dbus-tests

produces:
  failed  1/7  dbus-test00-availability-session (0.000124 sec)
   passed  2/7  dbus-test00-availability-system (0.003797 sec)
   passed  3/7  dbus-test01-type-conversion (0.000228 sec)
X11 connection rejected because of wrong authentication.
   passed  4/7  dbus-test02-register-service-own-bus (0.170745 sec)
  skipped  5/7  dbus-test02-register-service-session (0.000165 sec)
  skipped  6/7  dbus-test02-register-service-system (0.001415 sec)
  skipped  7/7  dbus-test03-peer-interface (0.000154 sec)
Ran 7 tests, 4 results as expected, 3 skipped

It would be good if the X11 attempt could be avoided.