[receiver/filelog] Log lines are reordered during file rotation

[swiatekm]

Describe the bug
When a file is rotated, filelog receiver may read lines from the new file before exhausting the old one, leading to log lines being reordered. This is a problem especially when using recombine to stitch multipart or multiline logs back together.

Steps to reproduce
Set a large interval length (5s for example), then rotate a file close to the end of it.

What did you expect to see?
Logs in the order they were written (and consistent with their timestamps).

What did you see instead?
Newer logs from the new file before older logs from the rotated file.

What version did you use?
v0.52.0 - v0.54.0, no change in behaviour between versions.

What config did you use?

receivers:
  filelog:
    poll_interval: 5s
    include:
    - /var/log/containers/*/*/*.log
  exporters:
    logging:
  service:
    telemetry:
      logs:
        level: debug
    pipelines:
      containers:
        receivers: [filelog]
        processors: []
        exporters: [logging]

Environment
OS: BottlerocketOS 1.8.0

Additional context
This came up in K8s, where container runtimes will split large log lines into parts, and the log collection agent needs to stitch them back together.

A fix is WIP here: #11889

[swiatekm]

Fixed in #11889