[CI] Shard four more AMD mirrors automatically (#61860)

Signed-off-by: Thang Nguyen <thangnguyenvn647@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.buildkite/test_areas/entrypoints.yaml

@@ -41,6 +41,7 @@ steps:
     amd:
       label: ":amd: (MI355 DPX) Entrypoints Unit"
       dind: false
+      automatic_shard: true
       device: mi355_dpx
       timeout_in_minutes: 50
       depends_on:
@@ -207,6 +208,7 @@ steps:
     amd:
       label: ":amd: (MI355 DPX) Entrypoints Integration (Speech to Text)"
       dind: false
+      automatic_shard: true
       device: mi355_dpx
       timeout_in_minutes: 60
       working_dir: "/vllm-workspace/tests"

.buildkite/test_areas/misc.yaml

@@ -32,6 +32,7 @@ steps:
     amd:
       label: ":amd: (MI355 DPX) V1 Sample"
       dind: false
+      automatic_shard: true
       device: mi355_dpx
       timeout_in_minutes: 70
       depends_on:

.buildkite/test_areas/pytorch.yaml

@@ -160,6 +160,7 @@ steps:
     amd:
       label: ':amd: (MI300) PyTorch Compilation Passes'
       dind: false
+      automatic_shard: true
       device: mi300_1
       timeout_in_minutes: 80
       working_dir: /vllm-workspace/tests