Enable forceExit for CLI tests

Author: koesie10

extensions/ql-vscode/test/vscode-tests/cli-integration/jest.config.ts

@@ -9,6 +9,8 @@ const config: Config = {
   // CLI integration tests call into the CLI and execute queries, so these are expected to take a lot longer
   // than the default 5 seconds.
   testTimeout: 180_000, // 3 minutes
+  // Ensure that Jest exits even when there are some remaining handles open
+  forceExit: true,
 };
 
 export default config;