Fix cloud-provider-extraction-migration/OWNERS file with correct structure

Signed-off-by: Davanum Srinivas <[email protected]>

Author: dims

sig-cloud-provider/cloud-provider-extraction-migration/OWNERS

@@ -8,7 +8,7 @@ approvers:
   - andrewsykim
   - cheftako
   - nckturner
-emeritus:
+emeritus_reviewers:
   - mcrute
 labels:
   - sig/cloud-provider