Fix: Resend BGP prefixes after setting allowas-in on tested device

In theory, the BGP session between the probe sending BGP updates with
"looped" AS path and the tested device (DUT) could be established
before Ansible configures 'allowas-in' on DUT. This fix adds an extra
'resend all prefixes' step to ensure the 'allowas-in' parameter is
applied to incoming BGP prefixes.

Author: ipspace

tests/integration/bgp.session/01-allowas-in.yml

@@ -59,6 +59,12 @@ validate:
     nodes: [ x1, x2, x3 ]
     plugin: bgp_neighbor(node.bgp.neighbors,'dut',af='ipv6')
 
+  resend:
+    description: Resend BGP prefixes from x2
+    nodes: [ x2 ]
+    devices: [ frr ]
+    exec: vtysh -c 'clear bgp * soft out'
+
   pfx_v4_allow:
     description: Check whether DUT disabled AS check on IPv4 EBGP session with X2
     wait: 5