nixos/test: some test fixes in succession of #125992

nixos/lib/test-driver/test-driver.py

···
         subtest=subtest,
         run_tests=run_tests,
         join_all=join_all,
+        retry=retry,
         serial_stdout_off=serial_stdout_off,
         serial_stdout_on=serial_stdout_on,
+        Machine=Machine,  # for typing
     )
     return general_symbols
 

nixos/tests/nsd.nix

···
         self = clientv4 if type == 4 else clientv6
         out = self.succeed(f"host -{type} -t {rr} {query}").rstrip()
         self.log(f"output: {out}")
+        import re
         assert re.search(
             expected, out
         ), f"DNS IPv{type} query on {query} gave '{out}' instead of '{expected}'"