This is a maintenance release fixing a regression issue with the course duplication feature and some other minor bugs. Plus, some database performance improvements have been introduced.

# - add index to learning_testquestanswer, learning_coursereport, core_field_userentry tables to speedup pages loading
# - fix course report test recalculation
#20091 - fix update item
#20090 - fix poll course completion when is setted as end course marker.
# - fix api course
# - fix prerequisites typo