unused code: Remove LoadCredentials function (#7369)

It is required to set the environment variable in the case of distributed
minio. LoadCredentials is used to notify peers of the change and will not work if
environment variable is set. so, this function will never be called.

cmd/admin-handlers.go

@@ -1480,14 +1480,6 @@ func (a adminAPIHandlers) UpdateAdminCredentialsHandler(w http.ResponseWriter,
 		return
 	}
 
-	// Notify all other Minio peers to update credentials
-	for _, nerr := range globalNotificationSys.LoadCredentials() {
-		if nerr.Err != nil {
-			logger.GetReqInfo(ctx).SetTags("peerAddress", nerr.Host.String())
-			logger.LogIf(ctx, nerr.Err)
-		}
-	}
-
 	// Reply to the client before restarting minio server.
 	writeSuccessResponseHeadersOnly(w)
 }