[1.6.x] Fixed #21415 -- Replaced escape sequence by literal non-breaking space

Unfortunately, escape sequences (\x.. or \u....) do not fit well
with the gettext toolchain. Falling back to using literal char,
even if visibility is not ideal.

Backport of 7e0ebd74c from master.
[1.6.x] Updated humanize translation catalog

Refs #21415