tests: Fix 'ICMP related with SNAT' test case in offload scenario.

This commit fixes the 'ICMP related with SNAT' test case when running
'make check-offloads'. The test case was flushing the datapath rules
and then checking the conntrack entries. In the TC offload case, this
was clearing the conntrack entries. This fix moves the conntrack entry
test before flushing the datapath rules.

Fixes: 7b74454 ("system-tests: Test openflow matching for ct related packets with SNAT.")
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Aaron Conole <aconole@redhat.com>

Author: chaudron

tests/system-traffic.at

@@ -7590,6 +7590,10 @@ dnl Solicit another "destination unreachable" response.
 dnl To verify that after flushing, the same openflow rules are matched.
 NS_CHECK_EXEC([at_ns0], [echo a | nc $NC_EOF_OPT -u 10.1.1.2 10000])
 
+AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.1.1.2) | sed -e 's/dst=10.1.1.2[[45]][[0-9]]/dst=10.1.1.2XX/'], [0], [dnl
+udp,orig=(src=10.1.1.1,dst=10.1.1.2,sport=<cleared>,dport=<cleared>),reply=(src=10.1.1.2,dst=10.1.1.2XX,sport=<cleared>,dport=<cleared>)
+])
+
 AT_CHECK([ovs-appctl revalidator/purge], [0])
 AT_CHECK([ovs-ofctl -O OpenFlow15 dump-flows br0 | ofctl_strip | ofctl_strip_bytes | sort | grep -v drop], [0], [dnl
  n_packets=1, priority=10,arp actions=NORMAL
@@ -7606,10 +7610,6 @@ AT_CHECK([ovs-ofctl -O OpenFlow15 dump-flows br0 | ofctl_strip | ofctl_strip_byt
 OFPST_FLOW reply (OF1.5):
 ])
 
-AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.1.1.2) | sed -e 's/dst=10.1.1.2[[45]][[0-9]]/dst=10.1.1.2XX/'], [0], [dnl
-udp,orig=(src=10.1.1.1,dst=10.1.1.2,sport=<cleared>,dport=<cleared>),reply=(src=10.1.1.2,dst=10.1.1.2XX,sport=<cleared>,dport=<cleared>)
-])
-
 AT_CHECK([tcpdump -n -v "icmp" -r p0.pcap 2>/dev/null | grep -E 'wrong|bad'], [1], [ignore-nolog])
 
 OVS_TRAFFIC_VSWITCHD_STOP