Limit Course Description text display in Course List block

[alexsanford]

See original request here - https://github.com/Automattic/sensei/pull/6324#issuecomment-1361383340

This is in relation to the Course List block, and specifically when using the "grid" pattern:

Would be great if we could limit the text we display as preview in each of the blocks as it messes up with alignment. I would limit the text/paragraph to have a preview of max 3 lines. That way, everything should align nicely.

Perhaps cutting off the text and using an ellipsis would be a good solution?

cc @Luchadores