ca: do not create copy of cert
ca: do not create copy of cert

It looks like it's unused

Signed-off-by: Alexander Morozov <2043cda4df124b840b98ee1c4307c199042efdf7@gmail.com>

cheyang/swarmkit,aaronlehmann/swarmkit,aaronlehmann/swarmkit,elifa/swarmkit,yongtang/swarmkit,diogomonica/swarmkit,fate-grand-order/swarmkit,docker/swarmkit,RenaudWasTaken/swarmkit,yp-engineering/swarmkit,Noyan759/swarmkit,alyyousuf7/swarmkit,fate-grand-order/swarmkit,diogomonica/swarmkit,deljuven/swarmkit,allencloud/swarmkit,jlhawn/swarmkit,cezarsa/swarmkit,deljuven/swarmkit,Noyan759/swarmkit,allencloud/swarmkit,sungwonh/swarmkit,AliyunContainerService/swarmkit,dperny/swarmkit-1,yongtang/swarmkit,cezarsa/swarmkit,jlhawn/swarmkit,elifa/swarmkit,cheyang/swarmkit,RenaudWasTaken/swarmkit,AliyunContainerService/swarmkit,yp-engineering/swarmkit,dperny/swarmkit-1,sungwonh/swarmkit,alyyousuf7/swarmkit,vasil-yordanov/swarmkit,vasil-yordanov/swarmkit,docker/swarmkit