fix(helpdesk): remove actor from dedup signature to prevent duplicate entries

SOAP entries often have an empty actor while OData entries have a code
like 'NKS'. After name resolution, one becomes 'Nikita Soldatov' and
the other stays empty — producing different signatures and causing
duplicates. The actor is not a reliable dedup field since the same
event can have different actor representations across sources.

Dedup now uses: ticket_no + timestamp_iso + type + message_hash.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/helpdesk/lib/Module/Helpdesk/Service/TicketCommunicationService.php

@@ -590,7 +590,6 @@ class TicketCommunicationService
             implode('|', [
                 (string) ($entry['ticket_no'] ?? ''),
                 (string) ($entry['timestamp_iso'] ?? ''),
-                (string) ($entry['actor'] ?? ''),
                 (string) ($entry['type'] ?? ''),
                 hash('sha256', (string) ($entry['message'] ?? '')),
             ])