fixup! build: remove ngcc postinstall patch in favor of separate script

Address feedback

Author: devversion

tools/bazel/update-ngcc-main-fields.js

@@ -1,10 +1,19 @@
 /**
- * Script that runs after node modules have been installed, and NGCC processed all packages.
- * This script updates the `package.json` files of `@angular` framework packages to point
- * to the NGCC processed UMD bundles. This is needed because we run Angular in a `nodejs_binary`,
- * but want to make sure that Ivy is being used. By default, the NodeJS module resolution will
- * load the unprocessed UMD bundle, so we update the `main` field in `package.json` files to point
- * to the Ivy UMD bundles.
+ * Script that runs after node modules have been installed, and Ngcc processed all packages.
+ * This script updates the `package.json` files of Angular framework packages to point to the
+ * Ngcc processed UMD bundles. This is needed because we run Angular in a `nodejs_binary`, but
+ * want to make sure that Ivy is being used. By default, the NodeJS module resolution will load
+ * the unprocessed UMD bundle because the `main` field of the `package.json` files point to the
+ * View Engine UMD bundles. This script updates the `main` field in `package.json` files to point
+ * to the previously generated Ivy UMD bundles.
+ *
+ * Ngcc does not by edit the `main` field because we ran it with the `--create-ivy-entry-points`
+ * flag. It instructs Ngcc to not modify existing package bundles, but rather create separate
+ * copies with the needed Ivy modifications. This is necessary because the original bundles
+ * are needed for View Engine, and we want to preserve them in order to be able to switch
+ * between Ivy and View Engine (for testing). Since the goal of this flag is to not modify
+ * any original package files/bundles, Ngcc will not edit the `main` field to point to
+ * the processed Ivy bundles.
  */
 
 const shelljs = require('shelljs');