Enable Tajik localization in prod

[janbrasna]

One-line summary

Adds tg to allowed locales in settings to stop 404ing in prod.

Significant changes and points to review

Following up from #15021, this is pending approval from l10ns.

This locale is still listed on the global root home page and offered to crawlers, but returns 404 as it is not explicitly allowed. (The reason is explained in both the previous PR and the linked issue.)

After an inquiry during the previous PR into the commitment of keeping Tajik version of wwwmo up to date, the community got very active the following months, and went from ~20% to currently 60%+ of translated content, with the usual key pages as home, products, browsers, vpn etc. above the threshold for enabling the locale. So the question is, whether also the Tajik locale wouldn't be a worthwhile addition, given its recent activity.

Issue / Bugzilla link

#15010

Testing

(in prod mode, with Debug=False & Dev=False)
http://localhost:8000/ (with Accept-Locale unset)
http://localhost:8000/404-locale/
http://localhost:8000/tg/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.07%. Comparing base (12806d5) to head (bca64f0).
Report is 262 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15784      +/-   ##
==========================================
- Coverage   79.07%   79.07%   -0.01%     
==========================================
  Files         160      160              
  Lines        8360     8359       -1     
==========================================
- Hits         6611     6610       -1     
  Misses       1749     1749              

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[alexgibson]

@peiying2 are we OK to enable this locale in production? Thanks

[maureenlholland]

@peiying2 following up here (apologies if I've missed a response in another channel) - can you confirm if we should add Tajik localization in production?

[janbrasna]

The translations don't look too bad:

https://www-dev.allizom.org/tg/?xv=legacy
https://www-dev.allizom.org/tg/firefox/
https://www-dev.allizom.org/tg/firefox/new/
https://www-dev.allizom.org/tg/firefox/browsers/mobile/focus/
https://www-dev.allizom.org/tg/firefox/features/
https://www-dev.allizom.org/tg/contribute/

@flodolo I know you're not PM for this locale, but have added it versions ago to the product — maybe you'd be able to facilitate the discussion to enable it for wwwmo prod, too? Thanks.

[flodolo]

Our internal documentation says that the threshold is 85%.

@peiying2 is out this week, and possibly the next as well. Since this isn't time-sensitive, I would wait until she's back, or check back at the end of next week.

[peiying2]

@janbrasna not sure if you or others are working on this. The community is pretty active even though it has not met the threshold yet. Let's go ahead and enable it on production.

[peiying2]

@alexgibson tg has crossed the 80% threshold today. Let's enable the locale on production when you get a chance. Not sure who is working on this ticket. Thank you.