Remove actor tag from event metrics across all modules

[vanrogu]

Summary

This change removes the "actor" tag from all event-related metrics throughout the event modeling framework. The actor field was being extracted from tracing information and used as a metric tag, but is now being removed to simplify metric cardinality and focus on channel-based tracking.

Key Changes

• BoundedContextImpl: Removed actor extraction and tag from both event() and incoming() methods' metrics for domain and inbound events
• InboundModule: Removed actor tag from translator metrics (counter and timer)
• OutboundModule: Removed actor tag from dispatcher metrics (counter and timer)
• ReadModelAdapter: Removed actor tag from read model event metrics (counter and timer)
• AggregateEventAppenderImpl: Removed actor tag from domain event metrics when appending aggregate events
• AggregateModule: Removed actor tag from aggregate load count metrics
• ExecuteCommandCommand: Removed actor tag from domain event metrics in DCB command execution

Implementation Details

• The actor variable extraction (tracing.actor() != null ? tracing.actor() : "unknown") has been completely removed from all locations
• Cache keys for metric lookups have been simplified by removing the actor component (e.g., eventName + ":" + actor + ":" + channel → eventName + ":" + channel)
• The "actor" tag has been removed from all Tags.of() and io.micrometer.core.instrument.Tags.of() calls
• The channel tag remains as the primary tracing dimension for metrics

https://claude.ai/code/session_01HW5m2CmCSTqTMtj5kgdhAV