Always emit Object type in decorator metadata for import type (#56594)

tests/cases/compiler/decoratorMetadataTypeOnlyImport.ts

@@ -0,0 +1,15 @@
+// @experimentalDecorators: true
+// @emitDecoratorMetadata: true
+
+// @filename: ./a.ts
+import { List } from 'unknown-module';
+export type MyList = List<number>;
+
+// @filename: ./b.ts
+import { type MyList } from './a';
+
+declare var Decorator: any;
+
+class Foo {
+  @Decorator myList?: MyList;
+}