fix: Update Dockerfiles with valid commit SHAs for chain tasks

- chain-001: Use real kubernetes/* commits from Feb 2026
- chain-002: Use istio 1.28.3, go-control-plane v0.14.0, and recent data-plane-api

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: LoCoBench Bot

benchmarks/ccb_crossrepo/crossrepo-chain-001/environment/Dockerfile

@@ -9,17 +9,17 @@ WORKDIR /workspace
 # Clone kubernetes/kubernetes
 RUN git clone https://github.com/kubernetes/kubernetes.git kubernetes && \
     cd kubernetes && \
-    git checkout 31bf3ed00ec0abe1b64d662d2e07e23e08f7cce0
+    git checkout 31bf3ed48b91b67e5003d8df1b3bd0b918d1fb94
 
 # Clone kubernetes/api (synced from k/k staging)
 RUN git clone https://github.com/kubernetes/api.git api && \
     cd api && \
-    git checkout 40341bbc11e31a8e5926cffe1c7a84d28a9ca5cb
+    git checkout f32ed1d60cf0787a512bebd6c06a4b84ae0b7cc7
 
 # Clone kubernetes/apimachinery
 RUN git clone https://github.com/kubernetes/apimachinery.git apimachinery && \
     cd apimachinery && \
-    git checkout 4b5c7c1a95ffb9c8c70ea8098b7a03e9d1d6c8e0
+    git checkout b2e9f88ff6d4c50c13061a53b1239c7707354eda
 
 # Verify repos exist
 RUN ls -la /workspace/ && \

benchmarks/ccb_crossrepo/crossrepo-chain-002/environment/Dockerfile

@@ -9,17 +9,17 @@ WORKDIR /workspace
 # Clone istio/istio
 RUN git clone https://github.com/istio/istio.git istio && \
     cd istio && \
-    git checkout 1.24.1
+    git checkout 4c1f845d839e9086ee85ad9337f2647492322eb4
 
 # Clone envoyproxy/go-control-plane
 RUN git clone https://github.com/envoyproxy/go-control-plane.git go-control-plane && \
     cd go-control-plane && \
-    git checkout v0.13.3
+    git checkout 71637ad69bbc5f51fbb2562e612a4365292804a5
 
 # Clone envoyproxy/data-plane-api (protobuf definitions)
 RUN git clone https://github.com/envoyproxy/data-plane-api.git data-plane-api && \
     cd data-plane-api && \
-    git checkout v3.36.0
+    git checkout 84e84367f2560cdb47b9bb78fd3e615feb80c3e4
 
 # Verify repos exist
 RUN ls -la /workspace/ && \