build: stop publishing @angular-devkit/build-optimizer to NPM

With this change we mark the deprecated `@angular-devkit/build-optimizer` package as a private and stop publishing it to NPM.

Author: alan-agius4

README.md

@@ -160,7 +160,6 @@ This is a monorepo which contains many tools and packages:
 |---|---|---|---|
 **Architect** | [`@angular-devkit/architect`](https://npmjs.com/package/@angular-devkit/architect) | [![latest](https://img.shields.io/npm/v/%40angular-devkit%2Farchitect/latest.svg)](https://npmjs.com/package/@angular-devkit/architect) | [![README](https://img.shields.io/badge/README--green.svg)](/packages/angular_devkit/architect/README.md) [![snapshot](https://img.shields.io/badge/snapshot--blue.svg)](https://github.com/angular/angular-devkit-architect-builds)
 **Build Angular** | [`@angular-devkit/build-angular`](https://npmjs.com/package/@angular-devkit/build-angular) | [![latest](https://img.shields.io/npm/v/%40angular-devkit%2Fbuild-angular/latest.svg)](https://npmjs.com/package/@angular-devkit/build-angular) | [![README](https://img.shields.io/badge/README--green.svg)](/packages/angular_devkit/build_angular/README.md) [![snapshot](https://img.shields.io/badge/snapshot--blue.svg)](https://github.com/angular/angular-devkit-build-angular-builds)
-**Build Optimizer** | [`@angular-devkit/build-optimizer`](https://npmjs.com/package/@angular-devkit/build-optimizer) | [![latest](https://img.shields.io/npm/v/%40angular-devkit%2Fbuild-optimizer/latest.svg)](https://npmjs.com/package/@angular-devkit/build-optimizer) | [![README](https://img.shields.io/badge/README--green.svg)](/packages/angular_devkit/build_optimizer/README.md) [![snapshot](https://img.shields.io/badge/snapshot--blue.svg)](https://github.com/angular/angular-devkit-build-optimizer-builds)
 **Build Webpack** | [`@angular-devkit/build-webpack`](https://npmjs.com/package/@angular-devkit/build-webpack) | [![latest](https://img.shields.io/npm/v/%40angular-devkit%2Fbuild-webpack/latest.svg)](https://npmjs.com/package/@angular-devkit/build-webpack) | [![README](https://img.shields.io/badge/README--green.svg)](/packages/angular_devkit/build_webpack/README.md) [![snapshot](https://img.shields.io/badge/snapshot--blue.svg)](https://github.com/angular/angular-devkit-build-webpack-builds)
 **Core** | [`@angular-devkit/core`](https://npmjs.com/package/@angular-devkit/core) | [![latest](https://img.shields.io/npm/v/%40angular-devkit%2Fcore/latest.svg)](https://npmjs.com/package/@angular-devkit/core) | [![README](https://img.shields.io/badge/README--green.svg)](/packages/angular_devkit/core/README.md) [![snapshot](https://img.shields.io/badge/snapshot--blue.svg)](https://github.com/angular/angular-devkit-core-builds)
 **Schematics** | [`@angular-devkit/schematics`](https://npmjs.com/package/@angular-devkit/schematics) | [![latest](https://img.shields.io/npm/v/%40angular-devkit%2Fschematics/latest.svg)](https://npmjs.com/package/@angular-devkit/schematics) | [![README](https://img.shields.io/badge/README--green.svg)](/packages/angular_devkit/schematics/README.md) [![snapshot](https://img.shields.io/badge/snapshot--blue.svg)](https://github.com/angular/angular-devkit-schematics-builds)

packages/angular_devkit/build_optimizer/package.json

@@ -3,6 +3,7 @@
   "version": "0.0.0-EXPERIMENTAL-PLACEHOLDER",
   "description": "Angular Build Optimizer",
   "experimental": true,
+  "private": true,
   "main": "src/index.js",
   "typings": "src/index.d.ts",
   "bin": {