Add audit event type definitions for flow trigger Create Update Destroy

What does this MR do and why?

• Emit flow_trigger_created, flow_trigger_updated, and flow_trigger_deleted audit events for all flow trigger Create/Update/Delete operations
• Extract inline destroy logic from the GraphQL Delete mutation into a new Ai::FlowTriggers::DestroyService for consistency and audit event support
• Add audit event emission to SyncBatchFoundationalFlowsService for bulk-inserted triggers during foundational flow sync
• Register three new audit event type definitions scoped to Project

Abstracted the common code into ee/app/services/ai/flow_triggers/base_service.rb, created a destroy variant for ease

The bulk audit event will individually create rather than a new bulk audit event

References

https://gitlab.com/gitlab-org/gitlab/-/work_items/593020

Screenshots or screen recordings

Before	After

How to set up and validate locally

Project > Automate > Triggers > New flow trigger/Edit flow trigger/Delete flow trigger.

MR acceptance checklist

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