Exception logs do not include TenantId when multitenancy is enabled

## Description

When running Elsa with multitenancy enabled, logged exceptions do not appear to include the current `TenantId`.

In a multitenant application, this makes it difficult to identify which tenant caused the failure. Since the same workflow/application instance can serve multiple tenants, exception logs should ideally include tenant context whenever a tenant is available.

## Expected Behavior

When an exception is logged while executing in a tenant context, the log entry should include the tenant id, for example as a structured logging property:

```text
TenantId:

Start by tracing exception logging during workflow execution and how the current tenant context is accessed. Reproduce an exception with multitenancy enabled, then verify that the log entry includes a structured TenantId when a tenant is available and remains valid without tenant context.

Written by the indexing model from the issue text.