Worker: chunk logs at 10kB instead of 1kB

Send logs in bigger chunks, otherwise a Blender render can cause too many
individual requests.

internal/worker/log_chunker.go

@@ -9,7 +9,7 @@ import (
 )
 
 // When the buffer grows beyond this many bytes, flush.
-const defaultLogChunkerBufferFlushSize = 1024
+const defaultLogChunkerBufferFlushSize = 10240
 
 // When the last flush was this long ago, flush.
 const defaultLogChunkerFlushMaxInterval = 30 * time.Second