Use prebuilt node.js on Docker image (mastodon#11768)

Dockerfile

@@ -7,19 +7,17 @@ SHELL ["bash", "-c"]
 ENV NODE_VER="12.9.1"
 RUN echo "Etc/UTC" > /etc/localtime && \
  apt update && \
- apt -y install wget make gcc g++ python && \
+ apt -y install wget python && \
  cd ~ && \
- wget https://nodejs.org/download/release/v$NODE_VER/node-v$NODE_VER.tar.gz && \
- tar xf node-v$NODE_VER.tar.gz && \
- cd node-v$NODE_VER && \
- ./configure --prefix=/opt/node && \
- make -j$(nproc) > /dev/null && \
- make install
+ wget https://nodejs.org/download/release/v$NODE_VER/node-v$NODE_VER-linux-x64.tar.gz && \
+ tar xf node-v$NODE_VER-linux-x64.tar.gz && \
+ rm node-v$NODE_VER-linux-x64.tar.gz && \
+ mv node-v$NODE_VER-linux-x64 /opt/node
 
 # Install jemalloc
 ENV JE_VER="5.2.1"
 RUN apt update && \
- apt -y install autoconf && \
+ apt -y install make autoconf gcc g++ && \
  cd ~ && \
  wget https://github.com/jemalloc/jemalloc/archive/$JE_VER.tar.gz && \
  tar xf $JE_VER.tar.gz && \