C2LC-434: Run 'npm rebuild' before Netlify build

[sbates-idrc]

Netlify builds are failing due to Netlify caching node-sass from npm install. When the version of Node is updated, Netlify continues to use the cached node_modules with the new version of Node. In the case of node-sass, the build done at npm install is Node version specific. And the caching of node-sass fails the build.

Example log of a failure from Netlify:

3:32:45 PM: $ npm run build
3:32:45 PM: > c2lc-coding-environment@0.9.0 build /opt/build/repo
3:32:45 PM: > react-scripts build
3:32:47 PM: Creating an optimized production build...
3:33:48 PM: Failed to compile.
3:33:48 PM: 
3:33:48 PM: ./src/index.scss
3:33:48 PM: Missing binding /opt/build/repo/node_modules/node-sass/vendor/linux-x64-72/binding.node
3:33:48 PM: Node Sass could not find a binding for your current environment: Linux 64-bit with Node.js 12.x
3:33:48 PM: Found bindings for the following environments:
3:33:48 PM:   - Linux 64-bit with Node.js 10.x
3:33:48 PM: This usually happens because your environment has changed since running `npm install`.
3:33:48 PM: Run `npm rebuild node-sass` to download the binding for your current environment.

[sbates-idrc]

See point 2 of https://answers.netlify.com/t/support-guide-my-site-deploy-fails-unless-netlifys-build-cache-is-cleared/3035

"2. Your dependencies have binary components, which need to be rebuilt for some reason. For instance, if the version of Node.js we use to build changes, any binary modules built against the old version are unlikely to work with the new version - BUT we also may not rebuild them if they are cached already!"

Point 10 "Build cache" of https://answers.netlify.com/t/support-guide-frequently-encountered-problems-during-builds/213 contains some information on what is cached.