tests/acceptance: skip s390x_ccw_vrtio_tcg on GitLab

Currently the test takes more the 900 seconds on GitLab and then times
out. Running on Travis seems to be OK.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200701135652.1366-27-alex.bennee@linaro.org>

tests/acceptance/boot_linux.py

@@ -20,6 +20,7 @@
 from avocado.utils import vmimage
 from avocado.utils import datadrainer
 from avocado.utils.path import find_command
+from avocado import skipIf
 
 ACCEL_NOT_AVAILABLE_FMT = "%s accelerator does not seem to be available"
 KVM_NOT_AVAILABLE = ACCEL_NOT_AVAILABLE_FMT % "KVM"
@@ -220,6 +221,7 @@ class BootLinuxS390X(BootLinux):
 
     chksum = '4caaab5a434fd4d1079149a072fdc7891e354f834d355069ca982fdcaf5a122d'
 
+    @skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab')
     def test_s390_ccw_virtio_tcg(self):
         """
         :avocado: tags=machine:s390-ccw-virtio