The container platform migration tries to deduce the platform data from
the containerd content store if it's available.
However, on Windows we currently default to a non-containerd runtime
setup, so the containerd client is nil and accessing its content store
paniced:
```
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x11b48e4]
goroutine 87 [running]:
github.com/containerd/containerd/v2/client.(*Client).ContentStore(0xc0003a0008?)
/go/src/github.com/docker/docker/vendor/github.com/containerd/containerd/v2/client/client.go:645 +0x24
github.com/docker/docker/daemon.(*Daemon).load(0xc00026e488, {0xc000c13d40, 0x40})
/go/src/github.com/docker/docker/daemon/container.go:84 +0x289
github.com/docker/docker/daemon.(*Daemon).restore.func1({0xc000c13d40, 0x40})
/go/src/github.com/docker/docker/daemon/daemon.go:236 +0x207
created by github.com/docker/docker/daemon.(*Daemon).restore in goroutine 1
/go/src/github.com/docker/docker/daemon/daemon.go:229 +0x1a7
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x11b48e4]
goroutine 90 [running]:
github.com/containerd/containerd/v2/client.(*Client).ContentStore(0xc000313608?)
/go/src/github.com/docker/docker/vendor/github.com/containerd/containerd/v2/client/client.go:645 +0x24
github.com/docker/docker/daemon.(*Daemon).load(0xc00026e488, {0xc000c13e00, 0x40})
/go/src/github.com/docker/docker/daemon/container.go:84 +0x289
github.com/docker/docker/daemon.(*Daemon).restore.func1({0xc000c13e00, 0x40})
/go/src/github.com/docker/docker/daemon/daemon.go:236 +0x207
created by github.com/docker/docker/daemon.(*Daemon).restore in goroutine 1
/go/src/github.com/docker/docker/daemon/daemon.go:229 +0x1a7
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x11b48e4]
```
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
