fix(@angular-devkit/build-angular): compile schema in synchronously

AJV only support a single schema with the same ID, compiling schemas async can cause a race condition were multiple schemas with the same name as compiled at the same time.

Closes #20847

(cherry picked from commit 43926a2)

Author: alan-agius4

packages/angular_devkit/core/src/json/schema/registry.ts

@@ -296,7 +296,7 @@ export class CoreSchemaRegistry implements SchemaRegistry {
     let validator: ValidateFunction;
     try {
       this._currentCompilationSchemaInfo = schemaInfo;
-      validator = await this._ajv.compileAsync(schema);
+      validator = this._ajv.compile(schema);
     } finally {
       this._currentCompilationSchemaInfo = undefined;
     }