integration-cli: fix netns test cleanup
integration-cli: fix netns test cleanup

1. Using MNT_FORCE flag does not make sense for nsfs. Using MNT_DETACH
though might help.

2. When -check.vv is added to TESTFLAGS, there are a lot of messages
like this one:

> unmount of /tmp/dxr/d847fd103a4ba/netns failed: invalid argument

and some like

> unmount of /tmp/dxr/dd245af642d94/netns failed: no such file or directory

The first one means directory is not a mount point, the second one
means it's gone. Do ignore both of these.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

cpuguy83/docker,Mokolea/docker,jlhawn/docker,nalind/docker,jthelin/docker,laijs/moby,jvanz/docker,ibuildthecloud/docker,x1022as/docker,kolyshkin/moby,moby/moby,kojiromike/docker,unclejack/docker,trebonian/docker,yosifkit/docker,dims/docker,trebonian/docker,Ramzec/docker,justincormack/docker,laijs/docker,pradipd/moby,x1022as/docker,kojiromike/docker,estesp/docker,Mokolea/docker,tmp6154/docker,jlhawn/docker,djs55/docker,jameszhan/docker,jwhonce/docker,flavio/docker,mikebrow/docker,cpuguy83/docker,estesp/docker,thaJeztah/docker,bearstech/moby,dims/docker,AkihiroSuda/docker,gnailuy/docker,AkihiroSuda/docker,gnailuy/docker,jimjag/docker,maxamillion/docker,vdemeester/docker,moby/moby,flavio/docker,thaJeztah/docker,mikebrow/docker,docker/docker,moul/docker,dims/docker,vdemeester/docker,YuPengZTE/docker,moul/docker,moby/moby,tmp6154/docker,kolyshkin/docker,docker/docker,dmcgowan/docker,konstruktoid/docker-upstream,konstruktoid/docker-upstream,SvenDowideit/docker,jthelin/docker,AkihiroSuda/docker,Mokolea/docker,rancher/docker,crosbymichael/docker,Mokolea/docker,bearstech/moby,jameszhan/docker,djs55/docker,konstruktoid/docker-1,yosifkit/docker,vdemeester/docker,gnailuy/docker,justincormack/docker,moby/moby,nalind/docker,rancher/docker,dmcgowan/docker,mahak/docker,estesp/docker,paralin/docker,laijs/moby,yongtang/docker,mahak/docker,kojiromike/docker,jameszhan/docker,jimjag/docker,jwhonce/docker,cpuguy83/docker,jwhonce/docker,djs55/docker,kolyshkin/moby,laijs/docker,yosifkit/docker,KarthikNayak/docker,jimjag/docker,maxamillion/docker,Ramzec/docker,Ramzec/docker,mahak/docker,crosbymichael/docker,unclejack/docker,flavio/docker,pradipd/moby,jvanz/docker,dmcgowan/docker,konstruktoid/docker-upstream,jimjag/docker,cpuguy83/docker,YuPengZTE/docker,nawawi/docker,rremer/moby,thaJeztah/docker,jlhawn/docker,KarthikNayak/docker,ibuildthecloud/docker,AkihiroSuda/docker,jvanz/docker,nawawi/docker,mikebrow/docker,trebonian/docker,x1022as/docker,rremer/moby,trebonian/docker,moul/docker,justincormack/docker,crosbymichael/docker,bearstech/moby,nawawi/docker,laijs/moby,Ramzec/docker,paralin/docker,rancher/docker,ibuildthecloud/docker,paralin/docker,mahak/docker,laijs/docker,nalind/docker,yongtang/docker,ibuildthecloud/docker,docker/docker,konstruktoid/docker-upstream,kolyshkin/docker,scotttlin/docker,scotttlin/docker,thaJeztah/docker,nalind/docker,paralin/docker,bearstech/moby,SvenDowideit/docker,yongtang/docker,rremer/moby,SvenDowideit/docker,YuPengZTE/docker,kolyshkin/moby,ibuildthecloud/docker,flavio/docker,gnailuy/docker,konstruktoid/docker-1,nawawi/docker,tmp6154/docker,KarthikNayak/docker,yosifkit/docker,unclejack/docker,pradipd/moby,scotttlin/docker,maxamillion/docker,moul/docker,konstruktoid/docker-1