Remove IAMSys dependency from IAMStorageAPI (#13436)

IAMSys is a higher-level object, that should not be called by the lower-level
storage API interface for IAM. This is to prepare for further improvements in
IAM code.

cmd/iam-dummy-store.go

@@ -81,10 +81,6 @@ func (ids *iamDummyStore) loadMappedPolicies(ctx context.Context, userType IAMUs
 	return nil
 }
 
-func (ids *iamDummyStore) loadAll(ctx context.Context, sys *IAMSys) error {
-	return sys.Load(ctx, ids)
-}
-
 func (ids *iamDummyStore) saveIAMConfig(ctx context.Context, item interface{}, path string, opts ...options) error {
 	return nil
 }
@@ -128,6 +124,3 @@ func (ids *iamDummyStore) deleteUserIdentity(ctx context.Context, name string, u
 func (ids *iamDummyStore) deleteGroupInfo(ctx context.Context, name string) error {
 	return nil
 }
-
-func (ids *iamDummyStore) watch(context.Context, *IAMSys) {
-}