containerd integration: verify behavior when switching snapshotters

[thaJeztah]

• relates to c8d: use the container's configured snapshotter where possible #45274
• relates to containerd integration: docker diff #44964 (comment)

Description

While we currently do not provide an option to specify the snapshotter to use
for individual containers (we may want to add this option in future), currently
it already is possible to configure the snapshotter in the daemon configuration,
which could (likely) cause issues when changing and restarting the daemon.

• image list: currently assumes that all images are using the same snapshotter
• some code paths may assume that the snapshotter didn't change (but the container
  may have been created with the previous snapshotter)

Other parts to verify;

• image save / load (if the intent is to use the loaded image for a container with a specific snapshotter)
• "docker pull" currently uses the default snapshotter. If the "docker pull" is done implicitly as part of a "docker run", we may have to pass this information along.
• "docker build" (both classic and BuildKit)