[BUG] if isCheckpointingEnabled =false ，offset commit will not get a chance to trigger

[holmes07]

Describe the bug
if checkpoint not turn on,the offset will never got commit, when we restart the job it will consumer from earliest offset again
can i fix it like this ? by commit it peroid

At ReaderThread run() method
After emitRecord(message) is call
// auto commit if checkpoint is not enable
if (!isCheckpointingEnabled && (SystemClock.now() - ackPeroid > lastAckTime)) {
offset.put(topicRange, message.getMessageId());
metadataReader.commitCursorToOffset(offset);
lastAckTime = SystemClock.now();
}

[KevinyhZou]

hello, I also encounter this problem in flink job consumed pulsar topic. And I have made a pr to enable offset auto commit. you can look at it: #497