[https://nvbugs/5474037][fix] Fix building tritonbuild/tritonrelease images (#7157)

Signed-off-by: Dimitrios Bariamis <[email protected]>
Signed-off-by: Dimitrios Bariamis <[email protected]>
Co-authored-by: Dimitrios Bariamis <[email protected]>

Author: dbari

docker/Dockerfile.multi

@@ -176,6 +176,7 @@ FROM wheel AS tritonbuild
 WORKDIR /src/tensorrt_llm
 RUN pip install /src/tensorrt_llm/build/tensorrt_llm*.whl
 COPY ./triton_backend/ ./triton_backend/
+ARG TRITON_BASE_TAG
 RUN bash ./triton_backend/inflight_batcher_llm/scripts/build.sh -s "r${TRITON_BASE_TAG%-py3}"