"EnableAPIGroupVersions" is set
The crd-remap-version plugin will always backup v1b1 resource for some
CRD. It impacts the feature flag `EnableAPIGroupVersions` which means to
backup all versions, and make migration fail.
In this commit the featureSet was removed from plugin server struct b/c
it blocks the parm `--features` to be populated correctly. This change
should not have negative impact b/c the attribute in server struct is never used.
Fixes#5146
Signed-off-by: Daniel Jiang <jiangd@vmware.com>