refactor(@angular-devkit/build-angular): remove Protractor builder and schematics

BREAKING CHANGE: Protractor is no longer supported.

Protractor was marked end-of-life in August 2023 (see https://protractortest.org/). Projects still relying on Protractor should consider migrating to another E2E testing framework, several support solid migration paths from Protractor.

* https://angular.dev/tools/cli/end-to-end
* https://blog.angular.dev/the-state-of-end-to-end-testing-with-angular-d175f751cb9c

Author: dgp1130

packages/angular_devkit/build_angular/builders.json

@@ -42,10 +42,10 @@
       "schema": "./src/builders/web-test-runner/schema.json",
       "description": "Run unit tests with Web Test Runner."
     },
-    "protractor": {
+    "private-protractor": {
       "implementation": "./src/builders/protractor",
       "schema": "./src/builders/protractor/schema.json",
-      "description": "Run protractor over a dev server."
+      "description": "PRIVATE API - Do not use."
     },
     "server": {
       "implementation": "./src/builders/server",

packages/schematics/angular/collection.json

@@ -23,10 +23,10 @@
       "schema": "./application/schema.json",
       "description": "Create an Angular application."
     },
-    "e2e": {
+    "private-e2e": {
       "factory": "./e2e",
       "schema": "./e2e/schema.json",
-      "description": "Create an Angular e2e application.",
+      "description": "PRIVATE API - Do not use.",
       "hidden": true
     },
     "class": {

packages/schematics/angular/utility/workspace-models.ts

@@ -30,7 +30,7 @@ export enum Builders {
   NgPackagr = '@angular-devkit/build-angular:ng-packagr',
   DevServer = '@angular-devkit/build-angular:dev-server',
   ExtractI18n = '@angular-devkit/build-angular:extract-i18n',
-  Protractor = '@angular-devkit/build-angular:protractor',
+  Protractor = '@angular-devkit/build-angular:private-protractor',
   BuildApplication = '@angular/build:application',
 }