Remove check-dbus-services test

The check-dbus-services aims to test all services configured as bus
activatable, however such a test is proving to be too naive and requires
significant investment to keep in a passing state.

There are an increasing number of services that have needed to be
blacklisted as they don't pass with reasonable rationale:

* Some require the ability to display a GUI and recieve a response that
  isn't currently viable with the current automated test platform nor is
  a GUI present on many of the image types.
* Some require specific devices to be present for the underlying service
  to start that isn't present in on the test systems.
* Some aren't completely installed and operational in the smaller cut-down
  images.

It has been decided that this test lacks sufficent benefit and significant
overhead and is thus being removed.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

test-cases/check-dbus-services.yaml

-metadata:
-  name: check-dbus-services
-  format: "Apertis Test Definition 1.0"
-  image-types:
-    minimal: [ armhf-internal, armhf, arm64, amd64 ]
-    target:  [ armhf-internal, amd64 ]
-    basesdk: [ amd64 ]
-    sdk:     [ amd64 ]
-  image-deployment:
-    - APT
-    - OSTree
-  type: sanity
-  exec-type: automated
-  priority: critical
-  maintainer: "Apertis Project"
-  description: "Service monitoring: verifying that every D-Bus service can be
-                activated successfully as a systemd unit is part of strategic
-                basic services functionality."
-
-  expected:
-    - "The output should be a succession of tests similar to that:"
-    - |
-        >---------------------------------------------------------------
-        + gdbus call --session -d org.xfce.Xfconf -o / -m org.freedesktop.DBus.Peer.Ping
-        ()
-        -> 0
-        + systemctl --full --no-ask-password --no-pager --user status xfconfd.service
-        ● xfconfd.service - XFCE configuration service
-           Loaded: loaded (/usr/lib/systemd/user/xfconfd.service; static; vendor preset: enabled)
-           Active: active (running) since Mon 2018-06-18 10:19:31 UTC; 21h ago
-         Main PID: 809 (xfconfd)
-           CGroup: /user.slice/user-1000.slice/user@1000.service/xfconfd.service
-                   └─809 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
-
-        Jun 18 10:19:31 apertis systemd[771]: Starting XFCE configuration service...
-        Jun 18 10:19:31 apertis systemd[771]: Started XFCE configuration service.
-        -> 0
-        vvvvvvvvvvvvvvvvvvvv
-        RESULT:pass:session_org.xfce.Xfconf.service: 
-        ^^^^^^^^^^^^^^^^^^^^
-    - "In this test results, the xfail are expected failures."
-    - |
-        >RESULT:xfail:session_FailToActivate: org.apertis.ApertisTests.FailToActivate should not have been activatable
-    - "If any test failed, they will be prefixed with:"
-    - |
-        >RESULT:fail:
-
-install:
-  git-repos:
-    - url: https://gitlab.apertis.org/tests/check-dbus-services.git
-      branch: 'apertis/v2019dev0'
-
-run:
-  steps:
-    - "# Enter test directory:"
-    - cd check-dbus-services
-    - "# Execute the following commands:"
-    - common/run-test-in-systemd --user=user bin/check-dbus-services
-    - common/run-test-in-systemd bin/check-dbus-services
-
-parse:
-  pattern: 'RESULT:(?P<result>\w+):(?P<test_case_id>[^:]+):'
-  # LAVA doesn't seem to have the concept of an expected failure,
-  # so calling it skipped is the next best thing
-  fixupdict:
-    xfail: skip