ci: add automatic retry

When merging PR on the project, it's possible to observe failures on CI
that can be related to sporadic test failures or infrastructure issues
(pod eviction with Kubernetes). As a result, it adds latency on the
process and workload for our top maintainers.

This patch sets an automatic retry (supported by gitlab out of the box),
so failing jobs are automatically retriggered.

It's important to note that in case there is a real test or build
failure, concerned jobs will run a second time, and fail again. That
said, it happens seldomly since sub maintainers are supposed to test for
this before sending it. Also, the retry is limited to the job that
failed, so it should be cheap in terms of CI minutes.

Acked-by: Richard Henderson <richard.henderson@linaro.org>
Link: https://lore.kernel.org/qemu-devel/20261020231602.24344-1-pierrick.bouvier@oss.qualcomm.com
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>

.gitlab-ci.d/base.yml

@@ -31,8 +31,9 @@ variables:
     # Ensure docker.py / tests/docker/Makefile.include always displays stdout
     # from any docker commands to aid debugging of failures
     DOCKER_V: 1
-
   interruptible: true
+  # automatic retry on failure (sporadic test failures or infra issues)
+  retry: 2
 
   rules:
     #############################################################