i915/ci: use debian-build-testing instead of debian-testing

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33345>
(cherry picked from commit f7e5daaedd)

.pick_status.json

@@ -684,7 +684,7 @@
         "description": "i915/ci: use debian-build-testing instead of debian-testing",
         "nominated": false,
         "nomination_type": 0,
-        "resolution": 4,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null,
         "notes": null

src/gallium/drivers/i915/ci/gitlab-ci.yml

@@ -4,7 +4,7 @@ include:
 # Manual test rules for using g33 in ondracka r300 farm.
 .ondracka-g33-test:
   extends:
-    - .b2c-x86_64-test-gl
+    - .b2c-x86_64-test-gl-manual # use debian-build-testing rather than debian-testing
     - .i915g-manual-rules
   tags:
     - intelgpu:codename:G33