remove obsolete scripts for python wheels (#8250)

Nowadays, this seems to be script where python wheels are being built:
https://github.com/protocolbuffers/protobuf/blob/ac63e80/kokoro/release/python/linux/build_artifacts.sh

Removing the obsolete scripts to avoid confusion.

Makefile.am

@@ -1397,10 +1397,6 @@ EXTRA_DIST = $(@DIST_LANG@_EXTRA_DIST)   \
   examples/pubspec.yaml                  \
   protobuf.bzl                           \
   protobuf_deps.bzl                      \
-  python/release/wheel/build_wheel_manylinux.sh  \
-  python/release/wheel/Dockerfile                \
-  python/release/wheel/protobuf_optimized_pip.sh \
-  python/release/wheel/README.md         \
   third_party/six.BUILD                  \
   third_party/zlib.BUILD                 \
   third_party/wyhash/LICENSE             \

python/release/wheel/Dockerfile

@@ -1,6 +0,0 @@
-FROM quay.io/pypa/manylinux1_x86_64
-
-RUN yum install -y libtool
-RUN /opt/python/cp27-cp27mu/bin/pip install twine
-
-COPY protobuf_optimized_pip.sh /

python/release/wheel/README.md

@@ -1,17 +0,0 @@
-Description
-------------------------------
-This directory is used to build released wheels according to PEP513 and upload
-them to pypi.
-
-Usage
-------------------------------
-For example, to release 3.3.0:
-    ./protobuf_optimized_pip.sh 3.3.0 PYPI_USERNAME PYPI_PASSWORD
-
-Structure
-------------------------------
-| Source                    | Source                                                       |
-|--------------------------------------|---------------------------------------------------|
-| protobuf_optimized_pip.sh | Entry point. Calling Dockerfile and build_wheel_manylinux.sh |
-| Dockerfile                | Build docker image according to PEP513.                      |
-| build_wheel_manylinux.sh  | Build wheel packages in the docker container.                |

python/release/wheel/build_wheel_manylinux.sh

@@ -1,27 +0,0 @@
-#!/bin/bash
-
-# Print usage and fail.
-function usage() {
-  echo "Usage: protobuf_optimized_pip.sh PROTOBUF_VERSION PYPI_USERNAME PYPI_PASSWORD" >&2
-  exit 1   # Causes caller to exit because we use -e.
-}
-
-# Validate arguments.
-if [ $0 != ./build_wheel_manylinux.sh ]; then
-  echo "Please run this script from the directory in which it is located." >&2
-  exit 1
-fi
-
-if [ $# -lt 3 ]; then
-  usage
-  exit 1
-fi
-
-PROTOBUF_VERSION=$1
-PYPI_USERNAME=$2
-PYPI_PASSWORD=$3
-
-docker rmi protobuf-python-wheel
-docker build . -t protobuf-python-wheel
-docker run --rm protobuf-python-wheel ./protobuf_optimized_pip.sh $PROTOBUF_VERSION $PYPI_USERNAME $PYPI_PASSWORD
-docker rmi protobuf-python-wheel

python/release/wheel/protobuf_optimized_pip.sh

@@ -1,66 +0,0 @@
-#!/usr/bin/env bash
-
-# DO NOT use this script manually! Called by docker.
-
-set -ex
-
-# Print usage and fail.
-function usage() {
-  echo "Usage: protobuf_optimized_pip.sh PROTOBUF_VERSION" >&2
-  exit 1   # Causes caller to exit because we use -e.
-}
-
-# Build wheel
-function build_wheel() {
-  PYTHON_VERSION=$1
-  PYTHON_BIN=/opt/python/${PYTHON_VERSION}/bin/python
-
-  $PYTHON_BIN setup.py bdist_wheel --cpp_implementation --compile_static_extension
-  auditwheel repair dist/protobuf-${PROTOBUF_VERSION}-${PYTHON_VERSION}-linux_x86_64.whl
-}
-
-# Validate arguments.
-if [ $0 != ./protobuf_optimized_pip.sh ]; then
-  echo "Please run this script from the directory in which it is located." >&2
-  exit 1
-fi
-
-if [ $# -lt 1 ]; then
-  usage
-  exit 1
-fi
-
-PROTOBUF_VERSION=$1
-PYPI_USERNAME=$2
-PYPI_PASSWORD=$3
-
-DIR=${PWD}/'protobuf-python-build'
-PYTHON_VERSIONS=('cp27-cp27mu' 'cp33-cp33m' 'cp34-cp34m' 'cp35-cp35m' 'cp36-cp36m')
-
-mkdir -p ${DIR}
-cd ${DIR}
-curl -SsL -O https://github.com/protocolbuffers/protobuf/archive/v${PROTOBUF_VERSION}.tar.gz
-tar xzf v${PROTOBUF_VERSION}.tar.gz
-cd $DIR/protobuf-${PROTOBUF_VERSION}
-
-# Autoconf on centos 5.11 cannot recognize AC_PROG_OBJC.
-sed -i '/AC_PROG_OBJC/d' configure.ac
-sed -i 's/conformance\/Makefile//g' configure.ac
-
-# Use the /usr/bin/autoconf and related tools to pick the correct aclocal macros
-export PATH="/usr/bin:$PATH"
-
-# Build protoc
-./autogen.sh
-CXXFLAGS="-fPIC -g -O2" ./configure
-make -j8
-export PROTOC=$DIR/src/protoc
-
-cd python
-
-for PYTHON_VERSION in "${PYTHON_VERSIONS[@]}"
-do
-  build_wheel $PYTHON_VERSION
-done
-
-/opt/python/cp27-cp27mu/bin/twine upload wheelhouse/*