remove unnecessary pkgs in Dockerfile

docker/Dockerfile

@@ -157,28 +157,5 @@ RUN mkdir -p /go/bin
 ENV GOPATH /go
 ENV PATH $PATH:$GOPATH/bin
 
-# Install python and tensorflow env for run test
-ARG CONDA_OS=Linux
-RUN cd / && curl -sL https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -o mconda-install.sh && \
-    bash -x mconda-install.sh -b -p miniconda && \
-    rm mconda-install.sh
-ENV PATH="/miniconda/bin:$PATH"
-
-RUN ls /miniconda/bin && /miniconda/bin/conda create -y -q -n sqlflow-dev python=3.6 && \
-    echo ". /miniconda/etc/profile.d/conda.sh" >> ~/.bashrc && \
-    echo "source activate sqlflow-dev" >> ~/.bashrc && \
-    bash -c "source activate sqlflow-dev && python -m pip install \
-    tensorflow==2.0.0-alpha0 \
-    mysql-connector-python \
-    impyla \
-    jupyter"
-# Install protobuf
-RUN wget --quiet https://github.com/protocolbuffers/protobuf/releases/download/v3.6.1/protoc-3.6.1-linux-x86_64.zip && \
-apt-get install -y unzip && \
-unzip -qq protoc-3.6.1-linux-x86_64.zip -d /usr/local && \
-rm protoc-3.6.1-linux-x86_64.zip && \
-go get github.com/golang/protobuf/protoc-gen-go && \
-mv /go/bin/protoc-gen-go /usr/local/bin/
-
 RUN echo "go get -t sqlflow.org/gohive && go test -v sqlflow.org/gohive" > /build_and_test.bash
 RUN chmod +x /build_and_test.bash