Fixes T6790. Turn the old method into "new" (old signature) and "newEphemeral". Deploy "newEphemeral" as many places as possible; basically places we are not in the Differential application *and* have no intentions of ever saving the diff. These callsites are also all places we are just trying to get some changesets at the end of the day.

set differential application policy to 'administrators only'. viewed a commit in diffusion and it worked without any errors! i'm just using my thinkin' noodle on the other code paths.