Remove event type key/filter links on the course calendar block

The course calendar block does not require the various event type keys/filters below the calendar, so these should be removed (so it will look similar to the "mini" dashboard calendar block).

It's worth mentioning that the colour coding from that is meaningless in the block (it does not use the colours), and I do not think the hide functionality works at all, so there doesn't seem to be any reason to retain this feature (it's also not necessary anywhere except the large, full calendar).