mcp: fix resource picker sometimes is empty (microsoft#250893)

We didn't trigger a 'change' after the promise resolved, so if we resolve rec.templates and rec.resources synchronously (for a server with no mcp resources) then we could end before publishing everything

Refs microsoft#250890

Author: connor4312

src/vs/workbench/contrib/mcp/browser/mcpResourceQuickAccess.ts

@@ -329,6 +329,7 @@ export class McpResourcePickHelper {
 				rec.templates.complete([]);
 				rec.resources.complete([]);
 			}
+			publish();
 		})).finally(() => {
 			store.dispose();
 		});