GH-1703 - Simplify JPA publication status defaulting

[char-yb]

Summary

• Simplify the default status assignment in JpaEventPublication.
• Remove an unreachable completionDate check from the constructor.

Details

JpaEventPublication previously initialized status with:

this.status = status != null ? status : completionDate != null ? Status.COMPLETED : Status.PROCESSING;

However, completionDate is an instance field, not a constructor parameter. During constructor execution it still has its default value, null, so the Status.COMPLETED branch is not reachable from this expression.

This change keeps the effective behavior and makes the defaulting logic explicit:

this.status = status != null ? status : Status.PROCESSING;