awslogs: remove unused eventBuffer update
We return immediately after this, so no need to update eventBuffer:
```
16:04:35 daemon/logger/awslogs/cloudwatchlogs.go:554:5: SA4006: this value of `eventBuffer` is never used (staticcheck)
16:04:35 				eventBuffer = eventBuffer[:0]
```
@@ -551,7 +551,6 @@ func (l *logStream) collectBatch(created chan bool) {
if !more {
// Flush event buffer and release resources
l.processEvent(batch, eventBuffer, eventBufferTimestamp)
- eventBuffer = eventBuffer[:0]
l.publishBatch(batch)
batch.reset()
return
