Update _test_alpn_tls_traffic metod

  Add retry for test connection to the loadbalancer.
  It allows to eliminate test fails when LB unreachable just after
  switching in ACTIVE state because keepalived didn't have time to
  check HA proxy state and update VIP address for loadbalancer

Related-Prod: PRODX-55468
Change-Id: I6651319434ea91fb1c10f490c69aa077c2d530c6
1 file changed