Remove noisy debug logs

The debug logs in the sync loop haven't been helpful so far, and they are quite
noisy pushing other logs out of the way, so this change removes them.

src/sync.js

@@ -711,7 +711,6 @@ SyncApi.prototype._syncFromCache = async function(savedSync) {
  * @param {boolean} syncOptions.hasSyncedBefore
  */
 SyncApi.prototype._sync = async function(syncOptions) {
-    debuglog("Starting sync request processing...");
     const client = this.client;
 
     if (!this._running) {
@@ -750,9 +749,7 @@ SyncApi.prototype._sync = async function(syncOptions) {
     // Reset after a successful sync
     this._failedSyncCount = 0;
 
-    debuglog("Storing sync data...");
     await client.store.setSyncData(data);
-    debuglog("Sync data stored");
 
     const syncEventData = {
         oldSyncToken: syncToken,
@@ -767,7 +764,6 @@ SyncApi.prototype._sync = async function(syncOptions) {
     }
 
     try {
-        debuglog("Processing sync response...");
         await this._processSyncResponse(syncEventData, data);
     } catch(e) {
         // log the exception with stack if we have it, else fall back