tests: fixed "Logical router policy packet marking"

The test was sometimes failing if an arp packet was received
after installing priority=0 flow, and before installing
the flow matching arp.

Signed-off-by: Xavier Simonart <xsimonar@redhat.com>
Acked-by: Mark Michelson <mmichels@redhat.com>
Signed-off-by: Dumitru Ceara <dceara@redhat.com>
(cherry picked from commit 66bea3a)

tests/ovn.at

@@ -24890,9 +24890,10 @@ OVS_WAIT_UNTIL([
 ])
 
 as hv1 check ovs-ofctl del-flows br-phys
+
 AT_DATA([flows.txt], [dnl
-table=0, priority=0 actions=NORMAL
 table=0, priority=200 arp,actions=drop
+table=0, priority=0 actions=NORMAL
 table=0, priority=100, pkt_mark=0x64 actions=drop
 table=0, priority=100, pkt_mark=0x2 actions=drop
 table=0, priority=100, pkt_mark=0x3 actions=drop