test zstd cache compression

Signed-off-by: Junpu Fan <junpu@amazon.com>

Author: junpuf

buildkite/test-template-ci.j2

@@ -280,7 +280,7 @@ steps:
         {% if vllm_use_precompiled == "1" %}
         --build-arg VLLM_MERGE_BASE_COMMIT={{ vllm_merge_base_commit }}
         {% endif %}
-        --cache-to type=registry,ref={{ cache_to }},mode=max
+        --cache-to type=registry,ref={{ cache_to }},mode=max,compression=zstd
         --cache-from type=registry,ref={{ cache_from }},mode=max
         --cache-from type=registry,ref={{ cache_from_base_branch }},mode=max
         --cache-from type=registry,ref={{ cache_from_main }},mode=max