Docker: Back to npm from yarn (#4730)

This commit reverts "Fix Dockerfile #4214" which uses yarn instead of npm.
The cause of the build error is that binding.gyp and src/crypto_key.cc
are missing when installing dependencies.
In other words, yarn did not fix build error.

There is no reason to use yarn, so go back to npm.

Dockerfile

@@ -21,12 +21,11 @@ RUN apk add --no-cache \
     pkgconfig \
     python \
     zlib-dev
-RUN npm i -g yarn
 
 COPY package.json ./
-RUN yarn install
+RUN npm i
 COPY . ./
-RUN yarn build
+RUN npm run build
 
 FROM base AS runner