dbus_message and dbus_service tests causing failure to ubuntu_qrt_apparmor test

In ubuntu_qrt_apparmor test, we check for lines begin with "Error:" and "Fatal Error:"

  if line.startswith("Error:") or line.startswith("Fatal Error:"):

And mark the test as failed accordingly.

However on Mantic, the dbus_message and dbus_service tests will complain about dbus-broker-launch not available if dbus-broker package was not installed:

running dbus_message
dbus[238536]: Unable to set up transient service directory: XDG_RUNTIME_DIR "/run/user/1000" is owned by uid 1000, not our uid 0
Error: dbus-broker-launch not available
Starting DBus Broker failed. Skipping tests...

running dbus_service
dbus[239313]: Unable to set up transient service directory: XDG_RUNTIME_DIR "/run/user/1000" is owned by uid 1000, not our uid 0
Error: dbus-broker-launch not available
Starting DBus Broker failed. Skipping tests...

PASSED: aa_exec access attach_disconnected at_secure introspect capabilities changeprofile onexec changehat changehat_fork changehat_misc chdir clone coredump deleted e2e environ exec exec_qual fchdir fd_inheritance fork i18n link link_subset mkdir mmap mount mult_mount named_pipe namespaces net_raw open openat pipe pivot_root posix_ipc ptrace pwrite query_label regex rename readdir rw socketpair swap sd_flags setattr symlink syscall sysv_ipc tcp unix_fd_server unix_socket_pathname unix_socket_abstract unix_socket_unnamed unix_socket_autobind unlink userns xattrs xattrs_profile longpath nfs dbus_eavesdrop dbus_message dbus_service dbus_unrequested_reply io_uring aa_policy_cache exec_stack nnp stackonexec stackprofile
FAILED:

Although these two tests were skipped and non of them were marked as FAILED in the test summary. The whole test will still be marked as failed because of the pattern we found in the test output.

This error message came from:
https://gitlab.com/apparmor/apparmor/-/commit/790b17e1dce5d834658c0e4410f19c0b4db4ef5b

Install the "dbus-broker" package can solve this issue (the tests are still being skipped)

I think the test should be marked as FAILED instead of skipped if the "dbus-broker" package is a must, and print out the error message to remind tester to install the package.