Handle deactivated special issues in EP Merge app

[mackhowell-nava]

Refinement notes:

• If there are deactivated special issues -- we might need an "abort" code in addition to success/fail.
• Not a need, but would make our metrics more clear. When we report results these get lumped into the "error" category, but deactivated special issues shouldn't be eligible for merging in the first place.
• Bigish lift ~1 week of work (integration + unit tests)
• We may not have a BIP endpoint to even check deactivated special issues (maybe a field in the contentions endpoint)
• In the past 2 weeks we've only had 6 jobs fail because of deactivated special issues.

[mackhowell-nava]

Contentions shouldn't have DSI (deactivated special issues) so it's inflating our error numbers at the moment in our metrics.