Hide emoji popup after multiple spaces or blank lines, closes #40620,#33678

What does this MR do?

Fixes a bug where typing multiple spaces in a row (or even a blank line) would not hide the emoji picker (see related issues).

This does not fix related issues, like #35925 (moved), #34949 (moved) and #40439 (moved).

Screenshots

What are the relevant issue numbers?

#40620 (closed),#33678 (closed)