Jenkinsfile: remove .git mount in stages that don't use it
Jenkinsfile: remove .git mount in stages that don't use it

The .git mount is only needed for the DCO check, and for building
the binaries if `DOCKER_GITCOMMIT` is not set.

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

paralin/docker,bearstech/moby,jimjag/docker,SvenDowideit/docker,kojiromike/docker,estesp/docker,cpuguy83/docker,moul/docker,paralin/docker,cpuguy83/docker,nalind/docker,trebonian/docker,kojiromike/docker,jvanz/docker,yosifkit/docker,vdemeester/docker,ibuildthecloud/docker,jvanz/docker,moby/moby,docker/docker,flavio/docker,dims/docker,AkihiroSuda/docker,djs55/docker,nalind/docker,bearstech/moby,mahak/docker,konstruktoid/docker-1,nawawi/docker,djs55/docker,gnailuy/docker,moby/moby,docker/docker,SvenDowideit/docker,dims/docker,gnailuy/docker,trebonian/docker,moul/docker,vdemeester/docker,jvanz/docker,Mokolea/docker,flavio/docker,trebonian/docker,thaJeztah/docker,konstruktoid/docker-upstream,flavio/docker,Ramzec/docker,Ramzec/docker,gnailuy/docker,jthelin/docker,cpuguy83/docker,jimjag/docker,tmp6154/docker,kolyshkin/moby,bearstech/moby,AkihiroSuda/docker,kolyshkin/moby,konstruktoid/docker-1,paralin/docker,tmp6154/docker,bearstech/moby,Mokolea/docker,ibuildthecloud/docker,SvenDowideit/docker,jthelin/docker,yongtang/docker,pradipd/moby,nawawi/docker,dims/docker,yongtang/docker,estesp/docker,kojiromike/docker,thaJeztah/docker,ibuildthecloud/docker,Mokolea/docker,AkihiroSuda/docker,nalind/docker,nawawi/docker,yosifkit/docker,mahak/docker,vdemeester/docker,paralin/docker,justincormack/docker,Ramzec/docker,jameszhan/docker,konstruktoid/docker-1,Mokolea/docker,trebonian/docker,jameszhan/docker,justincormack/docker,yosifkit/docker,nawawi/docker,jimjag/docker,justincormack/docker,tmp6154/docker,estesp/docker,moby/moby,konstruktoid/docker-upstream,yongtang/docker,djs55/docker,ibuildthecloud/docker,mahak/docker,thaJeztah/docker,Ramzec/docker,cpuguy83/docker,kolyshkin/moby,konstruktoid/docker-upstream,konstruktoid/docker-upstream,yosifkit/docker,mahak/docker,thaJeztah/docker,flavio/docker,AkihiroSuda/docker,moby/moby,moul/docker,pradipd/moby,nalind/docker,docker/docker,gnailuy/docker,pradipd/moby,jameszhan/docker,jimjag/docker,moul/docker,ibuildthecloud/docker