fix(xo-server): enable async_hooks support in Bluebird (#5635)

Necessary for `@xen-orchestra/backups`.

packages/xo-server/bin/xo-server

@@ -18,7 +18,14 @@ try {
 
 // Use Bluebird for all promises as it provides better performance and
 // less memory usage.
-global.Promise = require('bluebird')
+const Bluebird = require('bluebird')
+
+// Enable `async_hooks` because it's used by `@xen-orchestra/backups/Task` via `node-zone`
+//
+// See: http://bluebirdjs.com/docs/api/promise.config.html#async-hooks
+Bluebird.config({ asyncHooks: true })
+
+global.Promise = Bluebird
 
 require('@xen-orchestra/log/configure').catchGlobalErrors(require('@xen-orchestra/log').default('xo:xo-server'))