Should we remove the experimental tag from Shadow Replicas

[colings86]

This came up in fixItFriday when discussing #19798 and it was felt that in the case of shadow replicas it warrants it's own issue to discuss whether we still consider this experimental.

/cc @dakrone

[dakrone]

I think in order to remove the experimental tag from this, we should add a table with filesystems and whether they do or do not work with shadow replicas. IE, NFS doesn't work, but AzureFS does, etc

[javanna]

Support shadow replicas was removed, hence nothing to do here.