integration: remove lease exist checking on randomized expiry
integration: remove lease exist checking on randomized expiry

Lease with TTL 5 should be renewed with randomization,
thus it's still possible to exist after 3 seconds.

Signed-off-by: Gyu-Ho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

a-robinson/etcd,mqliang/etcd,etcd-io/etcd,mkumatag/etcd,li-ang/etcd,xiang90/etcd,visheshnp/etcd,dannysauer/etcd,sinsharat/etcd,joshix/etcd,armstrongli/etcd,YuleiXiao/etcd,whuwxl/etcd,glevand/coreos--etcd,fanminshi/etcd,sinsharat/etcd,mqliang/etcd,ajityagaty/etcd,mqliang/etcd,gyuho/etcd,joshix/etcd,heyitsanthony/etcd,whuwxl/etcd,rnaveiras/etcd,etcd-io/etcd,coreos/etcd,sebrandon1/etcd,rnaveiras/etcd,ajityagaty/etcd,bluebreezecf/etcd,gyuho/etcd,rnaveiras/etcd,vimalk78/etcd,lorneli/etcd,mickep76/etcd,YuleiXiao/etcd,glevand/coreos--etcd,a-robinson/etcd,mkumatag/etcd,li-ang/etcd,mkumatag/etcd,etcd-io/etcd,visheshnp/etcd,fanminshi/etcd,ajityagaty/etcd,bluebreezecf/etcd,akauppi/etcd,dannysauer/etcd,armstrongli/etcd,vimalk78/etcd,mickep76/etcd,cockroachdb/etcd,coreos/etcd,lorneli/etcd,xiang90/etcd,akauppi/etcd,sebrandon1/etcd,bdarnell/etcd,cockroachdb/etcd,heyitsanthony/etcd,bdarnell/etcd