refactor(core): make lockRunMode a noop and deprecate it.

BREAKING CHANGE:
- `lockRunMode` is deprecated and no more needed.

Closes #9878

modules/@angular/compiler-cli/integrationtest/test/init.ts

@@ -12,7 +12,3 @@ require('reflect-metadata');
 
 require('zone.js/dist/zone-node.js');
 require('zone.js/dist/long-stack-trace-zone.js');
-
-import {lockRunMode} from '@angular/core';
-// Need to lock the mode explicitely as this test is not using Angular's testing framework.
-lockRunMode();