Drop no-op updateSiteUrl call from WxrImporter

updateSiteUrl only rewrites the target site's own URL and returns early when it
is unchanged — which is always the case for a WXR merge (the DB keeps the
target URL, and the importer has no knowledge of the source URL). The call did
nothing but implied a capability it lacks. Replace it with a comment explaining
why internal links keep pointing at the source, matching the dashboard importer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/cli/lib/import-export/import/importers/wxr-importer.ts

@@ -11,7 +11,6 @@ import {
 import { runWpCliCommand } from 'cli/lib/run-wp-cli-command';
 import { ImportExportEventEmitter } from '../../events';
 import { BackupContents } from '../types';
-import { updateSiteUrl } from '../update-site-url';
 import { ensureDir, Importer, ImporterResult } from './importer';
 
 // Files staged into the site for the import are placed under this directory (at the
@@ -88,7 +87,11 @@ export class WxrImporter extends ImportExportEventEmitter implements Importer {
 
 			this.emit( ImportEvents.IMPORT_DATABASE_COMPLETE );
 
-			await updateSiteUrl( site );
+			// Note: no site-URL rewrite here. Unlike the SQL/backup importers (which
+			// replace the whole database with the source site's URL), a WXR merge leaves
+			// the target site's URL unchanged, and the importer has no knowledge of the
+			// source site's URL. Internal links inside imported posts therefore keep
+			// pointing at the source — matching the WordPress dashboard importer.
 
 			this.emit( ImportEvents.IMPORT_COMPLETE, 'xml' );
 			return {