Hey @loicmathieu

Summary

Updates the fix for invalid Unicode payload handling so malformed Unicode
does not still destabilize the instance.

This follows up on the reopened #14806 report that the issue was still
reproducible and could still kill the instance.

What changed

• guard DefaultLogEntryEmitter against unsupported queue payloads so
  invalid log entries are dropped instead of letting the async queue failure
  bubble out
• broaden PostgreSQL JSONB error detection in JdbcQueueClient so lone
  surrogate / invalid Unicode payload failures are converted into
  UnsupportedMessageException
• keep the worker-controller recovery path that strips outputs and retries
  when queue emission fails with UnsupportedMessageException
• add regression coverage for:
  • unsupported log-entry emission
  • lone high surrogate payloads
  • lone low surrogate payloads

Why

The previous handling covered some invalid payload cases, but malformed
Unicode could still escape through log emission. That left a crash path
open even after the earlier fix.

Notes:

• The Postgres queue regression test updates are included, but I could not
  fully run the Postgres-backed test class in this environment because no
  local PostgreSQL instance was available.

Related

• Closes invalid unicode sequence crashes kestra executor pod #14806