refactor(core): move amino registrar and drop legacy package (backport #21531) (#21561)

Co-authored-by: Julien Robert <julien@rbrt.fr>

x/group/module/module.go

@@ -10,7 +10,6 @@ import (
 	"google.golang.org/grpc"
 
 	"cosmossdk.io/core/appmodule"
-	"cosmossdk.io/core/legacy"
 	"cosmossdk.io/core/registry"
 	"cosmossdk.io/x/group"
 	"cosmossdk.io/x/group/client/cli"
@@ -88,8 +87,8 @@ func (AppModule) RegisterInterfaces(registrar registry.InterfaceRegistrar) {
 }
 
 // RegisterLegacyAminoCodec registers the group module's types for the given codec.
-func (AppModule) RegisterLegacyAminoCodec(cdc legacy.Amino) {
-	group.RegisterLegacyAminoCodec(cdc)
+func (AppModule) RegisterLegacyAminoCodec(registrar registry.AminoRegistrar) {
+	group.RegisterLegacyAminoCodec(registrar)
 }
 
 // RegisterInvariants does nothing, there are no invariants to enforce