tests/conftest: solve some totos

One todo is about not working flush but that was resolved by
84e6788e and thus no longer  relevant.

The second one is about DNS to be specified to ISP but that is already
set to local ISP's address.

tests/conftest.py

@@ -139,7 +139,7 @@ def fixture_client_board(board, board_serial, board_root_password, lan1_client):
     pexp.expect_exact("root@192.168.1.1's password:")
     pexp.sendline(board_root_password)
     pexp.expect_exact("root@turris:")
-    yield nsfarm.cli.Shell(pexp, flush=False)  # TODO drop this flush disable when it works
+    yield nsfarm.cli.Shell(pexp)
 
     board.set_serial_flush(False)
     board_serial.ctrl_c()  # Terminate tail -f on serial console
@@ -179,7 +179,7 @@ def fixture_board_wan(board, client_board, isp_container):
     client_board.run(f"uci set network.wan.ipaddr='{wan_ip}'")
     client_board.run("uci set network.wan.netmask='255.240.0.0'")
     client_board.run("uci set network.wan.gateway='172.16.1.1'")
-    client_board.run("uci set network.wan.dns='172.16.1.1'")  # TODO configure to ISP
+    client_board.run("uci set network.wan.dns='172.16.1.1'")
     client_board.run("uci commit network")
     client_board.run("/etc/init.d/network restart")
     client_board.run(f"while ! ip link show {board.wan} | grep -q ' state UP '; do sleep 1; done")