Add quota support in Backbeat

- Backbeat may send internal API requests that will evaluate
  quotas. This change fixes these scenarios, as they were
  trying to push finalizer hooks to an empty object.

Issue: CLDSRV-586

lib/routes/routeBackbeat.js

@@ -1372,6 +1372,10 @@ function routeBackbeat(clientIP, request, response, log) {
     _normalizeBackbeatRequest(request);
     const requestContexts = prepareRequestContexts('objectReplicate', request);
 
+    // Ensure backbeat operations like expiration can properly use quotas
+    // eslint-disable-next-line no-param-reassign
+    request.finalizerHooks = [];
+
     // proxy api requests to Backbeat API server
     if (request.resourceType === 'api') {
         if (!config.backbeat) {
@@ -1518,16 +1522,24 @@ function routeBackbeat(clientIP, request, response, log) {
             return backbeatRoutes[request.method][request.resourceType]
                 [request.query.operation](request, response, log, next);
         }],
-        err => {
-            if (err) {
-                return responseJSONBody(err, null, response, log);
-            }
-            log.debug('backbeat route response sent successfully',
-                { method: request.method,
-                    bucketName: request.bucketName,
-                    objectKey: request.objectKey });
-            return undefined;
-        });
+        err => async.forEachLimit(
+            // Finalizer hooks are used in a quota context and ensure consistent
+            // metrics in case of API errors. No operation required if the API
+            // completed successfully.
+            request.finalizerHooks,
+            5,
+            (hook, done) => hook(err, done),
+            () => {
+                if (err) {
+                    return responseJSONBody(err, null, response, log);
+                }
+                log.debug('backbeat route response sent successfully',
+                    { method: request.method,
+                        bucketName: request.bucketName,
+                        objectKey: request.objectKey });
+                return undefined;
+            },
+        ));
 }