Hope the in_tail's option "max_line_size" can support retain the head part of the log

### Is your feature request related to a problem? Please describe.

When I collect logs which has a big single line log. It cause OOM KILL fluentd in in_tail stage. So I upgrade my fluentd to v1.14.4 to use the option "max_line_size". It works nice to skip the big log.But now, I have a need to retain the head 50000 length of the big single log.

### Describe the solution you'd like

I hope there is a option to control the option "max_line_size" to retain the head length of the big single log.

### Describe alternatives you've considered

I don't want to skip the large log and hope to keep 50000 length. I have no idea to deal with it now.

### Additional context

_No response_