fix: ensure singlebeat identifier set correctly
Description
This PR fixes redis key prefix composition issues which put a _ at the end of the single beat identifier, which shouldn't happen.
Supporting information
Dependencies
N/A
Testing instructions
- Check that https://temp-lilac.opencraft.hosting/admin/instructor_task/instructortask/ is produced 1 minute tasks until March 31, 2022, 9:14 a.m.
Deadline
ASAP