Unalias bilingual/multilingual commentary

BUR #29877 has been approved by @nonamethanks.

remove alias bilingual_commentary -> mixed-language_commentary
remove alias multilingual_commentary -> mixed-language_commentary

The same as bilingual/multilingual, when the same text is present in multiple languages.

They were aliased in topic #21333 as "utility alias" and previously unused.

Example post #6527665, I already translated the Japanese part which is a translation of the Greek part so it should be bilingual_commentary commentary. It wouldn't make sense to have the same text twice or just delete the duplicate especially in a case like this where the Greek was a stylistic choice by the artist and not expected to be understood by their target audience.

I've always struggled with finding the correct way to tag this. I didn't realize we have bilingual and multilingual, with that in mind your solution makes perfect sense.

This bulk update request is pending automatic rejection in 5 days.

Nothing about "bilingual" or "multilingual" says that it's for the same sentence repeated in multiple languages. If we undo this alias then those tags are just going to become dumping grounds for random posts with two different languages in the commentary.

It seems to work just fine for the existing bilingual and multilingual tags for in-image text, no reason why commentary should be different.

The bulk update request #29877 (forum #298064) has been approved by @nonamethanks.

BUR #31620 has been approved by @nonamethanks.

create implication bilingual_commentary -> mixed-language_commentary
create implication multilingual_commentary -> mixed-language_commentary

Well we can try and see how it goes, and revert this if it goes out of hand. Feel free to populate these.

Splitting due to validation errors.

The bulk update request #31620 (forum #308131) has been approved by @nonamethanks.