do not store failed reqs

[dogancanbakir]

Closes #1953

$ go run . -u '168-this-does-not-exist.com' -sr -probe

    __    __  __       _  __
   / /_  / /_/ /_____ | |/ /
  / __ \/ __/ __/ __ \|   /
 / / / / /_/ /_/ /_/ /   |
/_/ /_/\__/\__/ .___/_/|_|
             /_/

                projectdiscovery.io

[INF] Current httpx version v1.6.8 (latest)
[WRN] UI Dashboard is disabled, Use -dashboard option to enable
http://168-this-does-not-exist.com [FAILED]

$ ree output
output
└── response
    └── index.txt

2 directories, 1 file

$  wc -c output/response/index.txt
       0 output/response/index.txt