daemon: remove redundant withResetAdditionalGIDs option

containerd's `WithUser` function now resets this property, starting with
[3eda46af12b1deedab3d0802adb2e81cb3521950][1] (v1.7.0-beta.4), so we no
longer need this function.

[1]: https://github.com/containerd/containerd/commit/3eda46af12b1deedab3d0802adb2e81cb3521950

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

daemon/exec_linux.go

@@ -4,7 +4,6 @@ import (
 	"context"
 
 	"github.com/containerd/containerd"
-	"github.com/containerd/containerd/containers"
 	"github.com/containerd/containerd/oci"
 	coci "github.com/containerd/containerd/oci"
 	"github.com/containerd/containerd/pkg/apparmor"
@@ -14,13 +13,6 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
-func withResetAdditionalGIDs() oci.SpecOpts {
-	return func(_ context.Context, _ oci.Client, _ *containers.Container, s *oci.Spec) error {
-		s.Process.User.AdditionalGids = nil
-		return nil
-	}
-}
-
 func getUserFromContainerd(ctx context.Context, containerdCli *containerd.Client, ec *container.ExecConfig) (specs.User, error) {
 	ctr, err := containerdCli.LoadContainer(ctx, ec.Container.ID)
 	if err != nil {
@@ -39,7 +31,6 @@ func getUserFromContainerd(ctx context.Context, containerdCli *containerd.Client
 
 	opts := []oci.SpecOpts{
 		coci.WithUser(ec.User),
-		withResetAdditionalGIDs(),
 		coci.WithAdditionalGIDs(ec.User),
 		coci.WithAppendAdditionalGroups(ec.Container.HostConfig.GroupAdd...),
 	}