ci/lavapipe: Add fractional NIR stress test job.

I think between the disk cache unit tests and testing that we can really
serialize/deserialize NIR, this covers what I cared about for testing disk
caching.

Closes: #3597
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10629>

src/gallium/frontends/lavapipe/ci/gitlab-ci.yml

@@ -8,3 +8,16 @@ lavapipe-vk:
     GPU_VERSION: lvp
     VK_DRIVER: lvp
     DEQP_FRACTION: 10
+
+lavapipe-nir-stress:
+  stage: software-renderer
+  extends:
+    - .test-vk
+    - .lavapipe-rules
+    - .deqp-test-vk
+  variables:
+    GPU_VERSION: lvp
+    VK_DRIVER: lvp
+    DEQP_FRACTION: 100
+    NIR_TEST_CLONE: "true"
+    NIR_TEST_SERIALIZE: "true"