[release/0.8] Revert containerd dep to 1.4.9

Due to some unfortunate deps in the root go.mod in containerd + some k8s staging
directory behavior, containerd 1.5 errors out when trying to get vendored into
kubernetes/kubernetes. Because we depend on ctrd 1.5, if hcsshim tries to
get bumped it will ask that we also bump their dep of containerd to 1.5
and things will fail also. This reverts our containerd dep for the release/0.8
branch to 1.4 so we're able to circumvent this, at least temporarily.

Issue tracking this problem that contains k8s proposed solution and statements on
this: kubernetes/kubernetes#104827

"Components that have a transitive dependency to anything in k8s.io/kubernetes,
including the staging components, can not be added as a dependency. The
detection and prevention of this in the dependency management scripts is
intentional."

While this work is temporary just to get k8s a new hcsshim release, longer
term we will need to find a way to trim our containerd dep either here, or
containerd will need to get rid of it's k8s.io/* dependencies in their root go.mod
to remove this circular import issue.

Signed-off-by: Daniel Canter <dcanter@microsoft.com>

go.mod

@@ -6,7 +6,9 @@ require (
 	github.com/Microsoft/go-winio v0.4.17
 	github.com/containerd/cgroups v1.0.1
 	github.com/containerd/console v1.0.2
-	github.com/containerd/containerd v1.5.1
+	github.com/containerd/containerd v1.4.9
+	github.com/containerd/continuity v0.1.0 // indirect
+	github.com/containerd/fifo v1.0.0 // indirect
 	github.com/containerd/go-runc v1.0.0
 	github.com/containerd/ttrpc v1.0.2
 	github.com/containerd/typeurl v1.0.2
@@ -19,6 +21,7 @@ require (
 	golang.org/x/sync v0.0.0-20201207232520-09787c993a3a
 	golang.org/x/sys v0.0.0-20210324051608-47abb6519492
 	google.golang.org/grpc v1.33.2
+	gotest.tools/v3 v3.0.3 // indirect
 )
 
 replace (