message: [docker] simplify validator-dynamic.Dockerfile
  The production build image already contains all necessary binaries, no
  need to rebuild them here.
  Closes:
  Approved by: zekun000
diff: -FROM debian:buster AS toolchain
  -
  -# To use http/https proxy while building, use:
  -# docker build --build-arg https_proxy=http://fwdproxy:8080 --build-arg http_proxy=http://fwdproxy:8080
  -
  -RUN apt-get update && apt-get install -y cmake curl clang git
  -
  -RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain none
  -ENV PATH "$PATH:/root/.cargo/bin"
  -
  -WORKDIR /libra
  -COPY rust-toolchain /libra/rust-toolchain
  -RUN rustup install $(cat rust-toolchain)
  -
  -FROM toolchain AS config_builder
  -
  -COPY . /libra
  -
  -RUN cargo build --release -p libra-node -p cli -p config-builder -p safety-rules && cd target/release && rm -r build deps incremental
  -
  ### Production Image ###
  FROM libra_e2e:latest as validator_with_config
  -COPY --from=config_builder /libra/target/release/config-builder /opt/libra/bin
  COPY docker/validator-dynamic/docker-run-dynamic.sh /
  COPY docker/validator-dynamic/docker-run-dynamic-fullnode.sh /
  