fix(logstash source): close the connection on a malformed frame

[bruceg]

Summary

A failed JSON decode or decompression was marked continuable (can_continue() == true), but the Lumberjack stream is length-prefixed binary with no resync marker. Continuing left the decoder desynchronized yet running: the uncompressed-JSON path never consumes the bad bytes (a CPU busy-loop) and the compressed path advances but keeps stale state, misframing subsequent bytes and emitting ACKs for bogus sequence numbers — surfacing as invalid sequence number received on the client.

Treat every decode error as fatal (can_continue() == false) so the connection closes and the client reconnects (fresh decoder) and retransmits the unacknowledged window. This matches the upstream logstash-input-beats server, which closes the channel on any decode exception, and is at-least-once and safe.

Adds decoder-level tests that malformed JSON and bad compression are fatal, and a socket-level test that a malformed frame closes the connection without sending an ACK. Also adds the missing authors line to the prior changelog fragment.

This was originally part of #25655 but I've broken it out here to simplify reviewing.

Vector configuration

How did you test this PR?

Unit tests are included

Change Type

• Bug fix
• New feature
• Dependencies
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

Related: #25655

Notes

• Please read our Vector contributor resources.
• Do not hesitate to use @vectordotdev/vector to reach out to us regarding this PR.
• Some CI checks run only after we manually approve them.
  • We recommend adding a pre-push hook, please see this template.
  • Alternatively, we recommend running the following locally before pushing to the remote branch:
    • make fmt
    • make check-clippy (if there are failures it's possible some of them can be fixed with make clippy-fix)
    • make test
• After a review is requested, please avoid force pushes to help us review incrementally.
  • Feel free to push as many commits as you want. They will be squashed into one before merging.
  • For example, you can run git merge origin master and git push.
• If this PR introduces changes Vector dependencies (modifies Cargo.lock), please
  run make build-licenses to regenerate the license inventory and commit the changes (if any). More details on the dd-rust-license-tool.