Exit pytest with error code 16 if ptfhost is unreachable#20539

wangxin merged 3 commits intosonic-net:mastersonic-net/sonic-mgmt:masterfrom

ZhaohuiS:ZhaohuiS/ptf_unreachableZhaohuiS/sonic-mgmt:ZhaohuiS/ptf_unreachableCopy head branch name to clipboard