RDE Fill Column will not allow a fill to be set for Level of Description

Likely as a result of changes made for https://github.com/archivesspace/archivesspace/pull/1705 , the Rapid Data Entry Fill Column feature will no longer allow for fill values to be set for Basic Information - Level of Description. While it was only intended that Basic Information - Level of Description should be grayed out/disabled in the column visibility dropdown, the change has disabled this selection in multiple unintended drop-downs.

See, specifically: https://github.com/archivesspace/archivesspace/blob/dd4b4ac03c7e1f7e204aab4b624c921e6b1ce372/frontend/app/assets/javascripts/rde.js#L994

A Fill Column value (Basic, not Sequence) should be able to be set for Level of Description.