Provide a missing feed transaction string for space creation

Summary:
Fixes T12502. This transaction probably should not be getting picked for feed rendering, but it currently does get selected in some cases.

This should probably be revisited eventually (e.g., when Maniphest moves to ModularTransactions) but just fix the brokenness for now.

Test Plan:

• Created a task in a space.
• Viewed feed.
• Saw the story render with readable text.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12502

Differential Revision: https://secure.phabricator.com/D17609