[hotfix] Remove custom task IDs and state.

# Purpose
Don't use custom task IDs or `PUBLISHED` state for file rendering task. @icereval and I discussed this and figured out that we don't actually need to prevent multiple render tasks from firing for the same file--the user sees the correctly rendered file even if multiple tasks run at once. This resolves #1356.

# Changes
* Remove custom task ID
* Remove custom task state

# Side effects
None expected