feature: optimize decodeLogRecord memory usage

[Orlion]

Optimize memory usage of decodeLogRecord using recordPool
Remove slice copy

[roseduan]

Thanks, but I think we can not use the record Pool because we will return the value from it.
And then the record will be reused in the pool, which may cause data inconsistency.

[Orlion]

Thanks, but I think we can not use the record Pool because we will return the value from it. And then the record will be reused in the pool, which may cause data inconsistency.

I removed recordPool.Put in some places to avoid data inconsistency, and in other places LogRecord has been copied out before Putting it back to the recordPool, so I think there is no problem of data inconsistency now. Please review again, Thanks.