[CI/Build] Give diffusion CPU tests more timeout headroom (#7983)

Signed-off-by: cr-gao <gaochenrui@sjtu.edu.cn>

.buildkite/cuda/test-merge.yml

@@ -18,7 +18,7 @@ steps:
         mirror_hardwares: l4_1
 
       - label: "Simple · Diffusion Test"
-        timeout_in_minutes: 20
+        timeout_in_minutes: 30
         commands:
           - "pytest -sv tests/diffusion -m 'core_model and cpu'"
         mirror_hardwares: l4_1

.buildkite/cuda/test-ready.yml

@@ -17,7 +17,7 @@ steps:
         mirror_hardwares: l4_1
 
       - label: "Simple · Diffusion Test"
-        timeout_in_minutes: 20
+        timeout_in_minutes: 30
         commands:
           - "pytest -sv tests/diffusion -m 'core_model and cpu'"
         mirror_hardwares: l4_1