Revert "fix catalan plural rules"

This reverts commit f1e471b561012f90938766c00aefff417593e71f.

I could not find any evidence that any dialect of Catalan has more than
two plural forms, nor could I find any other software project that gives
Catalan more than two plural forms. I personally have never heard or
seen more than two plural forms used in spoken or written communication.

The CLDR seems to agree with this.

[ChangeLog][Linguist][Important Behavior Changes] The plural rules for
Catalan have been fixed, which will invalidate any existing translations
with plurals.

Change-Id: Id71639a75ec970ee3079b468c2628ced710c1c3a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Alex Henrie <alexhenrie24@gmail.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>