Bug 1435067 - Use the pingsender when sending the sync ping r=gfritzsche,markh

MozReview-Commit-ID: 2x98suZvfr0

--HG--
extra : rebase_source : 7282863bbe33c46b124bddd9f870b3355789f0f7

services/sync/modules/telemetry.js

@@ -500,7 +500,7 @@ class SyncTelemetryImpl {
     if (record.syncs.length || numEvents) {
       log.trace(`submitting ${record.syncs.length} sync record(s) and ` +
                 `${numEvents} event(s) to telemetry`);
-      TelemetryController.submitExternalPing("sync", record);
+      TelemetryController.submitExternalPing("sync", record, { usePingSender: true });
       return true;
     }
     return false;