refactor(compiler): remove all source-level traces to tsc-wrapped (#18966)

- temporarily keeps the old sources under packages/tsc-wrapped
  until the build scripts are changed to use compiler-cli everywhere.
- removes the compiler options `disableTransformerPipeline` that was introduced
  in a previous beta of Angular 5, i.e. the transformer based compiler
  is now always enabled.

PR Close #18966

packages/bazel/src/ngc-wrapped/index.ts

@@ -5,6 +5,8 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+// TODO(tbosch): figure out why we need this as it breaks node code within ngc-wrapped
+/// <reference types="node" />
 import * as ng from '@angular/compiler-cli';
 import {BazelOptions, CachedFileLoader, CompilerHost, FileCache, FileLoader, UncachedFileLoader, constructManifest, debug, parseTsconfig, runAsWorker, runWorkerLoop} from '@bazel/typescript';
 import * as fs from 'fs';