Fix integration tests

[mxpv]

Follow up for #110
There are a couple of integration tests that we disabled on CI (#104) which require investigation:

• TestContainerPTY
• TestContainerExecLargeOutputWithTTY
• TestTaskUpdate
• TestTaskResize

We should fix the shim and enable them back.

[jsturtevant]

I was able to reproduce the first three but the last one works:

sudo TEST_RUNTIME="io.containerd.runc.v2-rs" EXTRA_TESTFLAGS="-run TestTaskResize" make integration

INFO[0000] running tests against containerd              
revision=3dce8eb055cbb6872793272b4f20ed16117344f8 runtime=io.containerd.runc.v2-rs snapshotter= version=1.6.21
INFO[0000] start to pull seed image                      image="ghcr.io/containerd/busybox:1.32"
=== RUN   TestTaskResize
=== PAUSE TestTaskResize
=== CONT  TestTaskResize
--- PASS: TestTaskResize (1.17s)

ok      github.com/containerd/containerd/integration/client     3.028s

[jsturtevant]

For TaskRisize I have a script that ran it continously and it is flaky:

on the 190th run locally:

INFO[0000] start to pull seed image                      image="ghcr.io/containerd/busybox:1.32"
=== RUN   TestTaskResize
=== PAUSE TestTaskResize
=== CONT  TestTaskResize
    container_test.go:2357: failed to create shim task: ttrpc: closed: unknown
containerd logs confirm it was during create:

time="2023-08-11T16:42:23.441614347Z" level=debug msg="event published" ns=testing topic=/snapshot/prepare type=containerd.events.SnapshotPrepare
time="2023-08-11T16:42:23.447312550Z" level=debug msg="get snapshot mounts" key=TestTaskResize
time="2023-08-11T16:42:23.460445957Z" level=debug msg="event published" ns=testing topic=/containers/create type=containerd.events.ContainerCreate
time="2023-08-11T16:42:23.486143669Z" level=debug msg="get snapshot mounts" key=TestTaskResize
time="2023-08-11T16:42:23.901091473Z" level=debug msg="garbage collected" d=7.965004ms
time="2023-08-11T16:42:27.508985837Z" level=info msg="shim disconnected" id=TestTaskResize