Correct rendering of workboard column move feed stories when a single transaction performs moves on multiple boards

Summary:
If a single transaction performs column moves on multiple different boards (which is permitted in the API), the rendering logic in the feed currently fails. Make it render properly.

Same fix as rPa3f4cbd7484b591425e83bbfc7642bccb04d0d57 for getTitle() which left out also fixing getTitleForFeed().

Test Plan: Carefully read the if/else logic.

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: avivey, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25646