Fix a JS error when adding a project card directly to a subproject from a workboard

Summary:
Fixes T12152. When creating a subproject task directly from a parent project, we can get column information back about the subproject column, which isn't visible. Just ignore this rather than trying to draw a card into a column which does not exist.

This flow (see test plan) is a little unintuitive since the card never appears on the workboard, but this class of things is probably roughly somewhere in T4900.

Test Plan:

• Create a parent project A.
• Create subproject B.
• On the workboard for A, select "Create Task..." from the dropdown.
• Add tag "B" in the dialog that pops up.
• Save the task.

Note that this flow creates a task tagged only with "B", since "A" and "B" are mutually exclusive tags.

Before patch: UI freezes (JX.Mask is never removed), JS error in console.
After patch: workflow completes. Note that card is (correctly) not visible: it's in an invisible subproject column.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12152

Differential Revision: https://secure.phabricator.com/D17242