[PD] Fix broken NIXL EP installation (#42542)

Signed-off-by: Ovidiu Mara <ovidium@nvidia.com>
(cherry picked from commit cca32d55a2)

docker/Dockerfile

@@ -846,9 +846,6 @@ RUN --mount=type=cache,target=/root/.cache/uv \
                 libcublas-dev-${CUDA_VERSION_DASH} \
                 libcusolver-dev-${CUDA_VERSION_DASH}"; \
     if [ "$INSTALL_KV_CONNECTORS" = "true" ]; then \
-        if [ "$CUDA_MAJOR" -ge 13 ]; then \
-            uv pip install --system nixl-cu13; \
-        fi; \
         uv pip install --system -r /tmp/kv_connectors.txt --no-build || ( \
             # if the above fails, install from source
             apt-get update -y && \
@@ -858,6 +855,8 @@ RUN --mount=type=cache,target=/root/.cache/uv \
             # clean up -dev packages, keep runtime libraries
             rm -rf /var/lib/apt/lists/* \
         ); \
+        # Force-reinstall the matching CUDA wheel so the correct nixl_ep_cpp.so is installed.
+        uv pip install --system --force-reinstall --no-deps nixl-cu${CUDA_MAJOR}; \
     fi
 
 ENV VLLM_USAGE_SOURCE production-docker-image