gitlab: ensure docker output is always displayed in CI

Set the new $(DOCKER_V) variable from the previous commit, so that any
CI jobs invoking docker will show the full stdout content. This improves
the ability to diagnose any build failures in CI that involve docker.

For example, when a 'docker build' command fails, it lets us see which
command in the Dockerfile failed and why.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20260210163556.713841-5-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.gitlab-ci.d/base.yml

@@ -28,6 +28,9 @@ variables:
     # we don't need. The --filter options avoid blobs and tree references we aren't going to use
     # and we also avoid fetching tags.
     GIT_FETCH_EXTRA_FLAGS: --filter=blob:none --filter=tree:0 --no-tags --prune --quiet
+    # Ensure docker.py / tests/docker/Makefile.include always displays stdout
+    # from any docker commands to aid debugging of failures
+    DOCKER_V: 1
 
   interruptible: true