test: use 'grep -E' for non-standard 'egrep'
test: use 'grep -E' for non-standard 'egrep'

Fix shellcheck complaints.

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

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