[202012][route] Fix random loss of arp info in test_static_route_ecmp #6614#6615

yaqiangz merged 2 commits intosonic-net:202012sonic-net/sonic-mgmt:202012from

yaqiangz:azure-202012_fix_test_static_route_ecmpyaqiangz/sonic-mgmt:azure-202012_fix_test_static_route_ecmpCopy head branch name to clipboard