[BUG] ListOffset return wrong value

[aloyszhang]

Describe the bug
Currently, KoP return wrong value when process ListOffsetRequest.

To Reproduce

1. start pulsar broker with KoP
2. send some message to broker
3. ListOffsetRequest for specified timstamp

Expected behavior
KoP should return the right value for ListOffsetRequest

Additional context
For example, we produce 4 message with timestamp

 timestamp for message 0 is 2
 timestamp for message 1 is 4
 timestamp for message 2 is 6
 timestamp for message 3 is 8

and do ListOffsetRequest test ， offset result are following

offset for earliest 0
 offset for latest 4
 offset for time  2 is 0
 offset for time  3 is 0
 offset for time  4 is 1
 offset for time  5 is 1
 offset for time  6 is 2
 offset for time  7 is 2
 offset for time  8 is 3
 offset for time  9 is 3

As we can see from the result, when timestamp is 3, 5, 7, 9, the offset result should be 1, 2, 3, 4, but found 0, ,1, 2,3