use json unmarshal/marshal from jsoniter in hotpaths (#12269)

cmd/admin-bucket-handlers.go

@@ -24,6 +24,7 @@ import (
 	"net/http"
 
 	"github.com/gorilla/mux"
+	jsoniter "github.com/json-iterator/go"
 	"github.com/minio/madmin-go"
 	"github.com/minio/minio/cmd/logger"
 	iampolicy "github.com/minio/minio/pkg/iam/policy"
@@ -154,6 +155,7 @@ func (a adminAPIHandlers) SetRemoteTargetHandler(w http.ResponseWriter, r *http.
 		return
 	}
 	var target madmin.BucketTarget
+	var json = jsoniter.ConfigCompatibleWithStandardLibrary
 	if err = json.Unmarshal(reqBytes, &target); err != nil {
 		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErrWithErr(ErrAdminConfigBadJSON, err), r.URL)
 		return