Removed two unnecessary cache roundtrips after a getAccount() call

The getAccount() call was resulting in two seemingly unnecessary cache roundtrips - the first where cache.ttl === cache tti (no need for a cache set operation to update the lastAccessedAt attribute in that case as ttl expiry would cover tti expiry), secondly in DataStore.prototype._wrapGetResourceResponse where data had been received from the cache rather than a request and therefore did not need to be immediately (re)cached.