Port containerd config imports to AL2023

[yndai]

What would you like to be added:

Port the change to import custom containerd overrides from #1630 which was done for AL2 for AL2023 AMIs

Why is this needed:

Some popular tooling such as Spegel uses the import directory to override settings: https://github.com/spegel-org/spegel/blob/main/docs/COMPATIBILITY.md#eks which is safer than doing something like sed

[cartermckinnon]

The NodeConfig accepts arbitrary additional config for containerd, we have an example in the docs for doing this exact thing (changing discard_unpacked_layers): https://awslabs.github.io/amazon-eks-ami/nodeadm/doc/examples/#configuring-containerd