fix(compiler): don’t use ng:// in AOT source maps, and never point to the original source file

This is important to not confuse users nor downstream tools that
consume our source maps. For generated content for which we don’t
have an original source file, we use the generated file now.

Fixes #19538

packages/compiler/src/aot/generated_file.ts

@@ -6,7 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {sourceUrl} from '../compile_metadata';
 import {Statement, areAllEquivalent} from '../output/output_ast';
 import {TypeScriptEmitter} from '../output/ts_emitter';
 
@@ -45,6 +44,5 @@ export function toTypeScript(file: GeneratedFile, preamble: string = ''): string
   if (!file.stmts) {
     throw new Error(`Illegal state: No stmts present on GeneratedFile ${file.genFileUrl}`);
   }
-  return new TypeScriptEmitter().emitStatements(
-      sourceUrl(file.srcFileUrl), file.genFileUrl, file.stmts, preamble);
+  return new TypeScriptEmitter().emitStatements(file.genFileUrl, file.stmts, preamble);
 }