Add more proxy environment variable tests
Add more proxy environment variable tests

It hasn't been easy to test proxying HTTPS URLs until the previous
change to allow proxying to HTTPS destinations without tunneling.

h1bomb/request,Aloomaio/request,LoicMahieu/request,cvibhagool/request,Jonekee/request,request/request,xiwc/request,kevinburke/request,h1bomb/request,pho3nixf1re/request,Aloomaio/request,longwenjunjie/request,motopia/request,wangchi/request,faradayio/request,phillipj/request,lalitkapoor/request,simov/request,paulomcnally/request,request/request,lxe/request,neo-z/request,MofeLee/request,pablobrady/request,kmulvey/request,sean3z/request,not001praween001/request,kublaj/request,faradayio/request,whembed197923/request,wakermahmud/request,rbramwell/request,udp/request,jsifuentes/request,Codelegant92/request,longwenjunjie/request,watson/request,nishant8BITS/request,linalu1/request,robu3/request,niklabh/request,kevinburke/request,kmulvey/request,IbpTeam/node-request,seegno-forks/request,HAKASHUN/request,niklabh/request,beni55/request,manishnakar/request,czardoz/request,neo-z/request,NewGyu/request,calibr/request,jsifuentes/request,seegno-forks/request,calibr/request,kublaj/request,ryanwholey/request,zhouweiming/request,xtidt/request,nishant8BITS/request,chaoliu/request,paulomcnally/request,wakermahmud/request,MofeLee/request,mvnnn/request,djchie/request,udp/request,zodsoft/request,jzaefferer/request,xiwc/request,czardoz/request,sean3z/request,wangchi/request,IveWong/request,whembed197923/request,pho3nixf1re/request,zhouweiming/request,jzaefferer/request,IbpTeam/node-request,blabno/request,simov/request,not001praween001/request,ryanwholey/request,NewGyu/request,linalu1/request,Codelegant92/request,manishnakar/request,zodsoft/request,beni55/request,mvnnn/request,watson/request,LoicMahieu/request,rbramwell/request,cvibhagool/request,Jonekee/request,Prasanna-sr/request,HAKASHUN/request,IveWong/request,lxe/request,pablobrady/request,motopia/request,Prasanna-sr/request,lalitkapoor/request,chaoliu/request,robu3/request,phillipj/request,blabno/request,xtidt/request,djchie/request