Build-image: Once the Netlify Build beta goes GA, remove `zip-it-and-ship-it` code

[ehmicky]

With Netlify Build beta, zip-it-and-ship-it is now called by @netlify/build programmatically from Node.js. Therefore, once we remove the Netlify Build beta feature flag, we will be able to remove the following pieces of code from the buildbot and the build-image:

• Installing zip-it-and-ship-it in the Dockerfile
• Allow configuring the zip-it-and-ship-it version (for debugging) with the ZISI_VERSION. This undocumented feature is not supported in Netlify Build at the moment. On the other hand, since zip-it-and-ship-it is now a moving part inside @netlify/build, we can use NETLIFY_BUILD_CLI_VERSION to specify the version of @netlify/build, therefore the version of zip-it-and-ship-it as well.

[2color]

Not sure if this belongs here. But I just discovered defining ZISI_VERSION does not properly change the version of zip-it-and-ship-it used.

This is using the normal build image without Netlify Build.

See https://app.netlify.com/sites/netlify-prisma-test/deploys/5e8b03af25d447000671ce08

[ehmicky]

@2color You can also upgrade to the latest version of zip-it-and-ship-it by opting in our latest beta.

[verythorough]

@ehmicky @Benaiah I'm moving this to the fast-follow milestone. Can you help assign it to the appropriate person?

[Benaiah]

@verythorough @ehmicky Sure, I can pick up this issue.