[19.03 backport] Integration: change signatures to fix golint warnings

[thaJeztah]

Built on top of #279 ("[19.03 backport] Handle the error case when a container reattaches to the same network") first two commits are from that PR

backports of:

• Integration: change signatures to fix golint warnings moby/moby#39332 Integration: change signatures to fix golint warnings
• integration: get tests to compile again moby/moby#39359 integration: get tests to compile again

Some conflicts in test files when backporting the first PR (moby#39332);

• conflict in first commit, due to Add alias for hostname if hostname != container name moby/moby#39204 ("Add alias for hostname if hostname != container name") not being in 19.03 (thus a test missing that was being modified)

• conflict in second commit, due to Start containers in their own cgroup namespaces moby/moby#38377 (Start containers in their own cgroup namespaces) feature not being in 19.03;

  Unmerged paths:
    (use "git add/rm <file>..." as appropriate to mark resolution)
  
  	deleted by us:   integration/container/run_cgroupns_linux_test.go
  	both modified:   integration/internal/container/container.go
  

• conflict in third commit (due to the same feature missing);

  Unmerged paths:
    (use "git add/rm <file>..." as appropriate to mark resolution)
  
  	deleted by us:   integration/container/run_cgroupns_linux_test.go
  	both modified:   integration/container/run_linux_test.go
  	both modified:   integration/internal/container/container.go
  

Conflicts were not too difficult to resolve

[thaJeztah]

Marked as WIP because #279 should be merge first (but we could merge this one instead fo get both changes in at once)

[thaJeztah]

rebased, now that #279 was merged

@kolyshkin @andrewhsu this is ready for review/merge

[thaJeztah]

rebased again because Jenkins logs were purged

[thaJeztah]

@kolyshkin ptal

[thaJeztah]

Hm.. might've missed a cherry-pick

01:29:36 # github.com/docker/docker/integration/container [github.com/docker/docker/integration/container.test]
01:29:36 integration/container/copy_test.go:108:25: cannot use t (type *testing.T) as type context.Context in argument to "github.com/docker/docker/integration/internal/container".Create:
01:29:36 	*testing.T does not implement context.Context (missing Deadline method)
01:29:36 integration/container/copy_test.go:108:25: cannot use ctx (type context.Context) as type *testing.T in argument to "github.com/docker/docker/integration/internal/container".Create

[thaJeztah]

Looks like that needs moby#39357

[thaJeztah]

oh, no, I see: needs a revert of 8f4b96f (last commit from #280)

[thaJeztah]

this is now failing because this branch is broken, and will be fixed by #374 (which depends on this PR)

[andrewhsu]

LGTM