CI: Use different git-directories for concurrent runners

When running multiple runners on the same machine, each git repo should
be in its own place to avoid them interfering with either other.

Link to docs:

https://docs.gitlab.com/ee/ci/runners/configure_runners.html#custom-build-directories

Series-to: u-boot
Series-cc: trini
Series-version: 2
Series-links: 442655
Series-changes: 3
- Use GIT_CLONE_PATH instead

Series-changes: 2
- Put this under the global 'default' part
END

Signed-off-by: Simon Glass <sjg@chromium.org>

.gitlab-ci.yml

@@ -5,6 +5,7 @@ variables:
   MIRROR_DOCKER: docker.io
   SJG_LAB: ""
   PLATFORM: linux/amd64,linux/arm64
+  GIT_CLONE_PATH: $CI_BUILDS_DIR/$CI_CONCURRENT_ID/u-boot
 
 default:
   tags:
@@ -12,6 +13,9 @@ default:
   # Grab our configured image.  The source for this is found
   # in the u-boot tree at tools/docker/Dockerfile
   image: ${MIRROR_DOCKER}/trini/u-boot-gitlab-ci-runner:jammy-20240911.1-08Dec2024
+  services:
+    - name: container-$(CI_JOB_ID)
+      command: ["--rm"]
 
 # We run some tests in different order, to catch some failures quicker.
 stages: