Windows: Cleanup rm- prefixed layers
Windows: Cleanup rm- prefixed layers

Some layers might be prefixed with rm-, which will result
in an error when converting that string into an integer.

Signed-off-by: Claudiu Belu <af739d2f4a05c59b6221d22d4e3a86ff2cbe39c4@cloudbasesolutions.com>

dmcgowan/containerd,mikebrow/containerd,containerd/containerd,estesp/containerd,thaJeztah/containerd,dmcgowan/containerd,thaJeztah/containerd,estesp/containerd,containerd/containerd,mikebrow/containerd