By default, only build non-HTML docs for switcher languages

[hugovk]

The docs build server builds a lot of docs for many languages and versions, and takes up a lot of time.

This means after a docs change, it can take a long time to get those changes available for our readers.

Right now we have:

• 16 languages
• 4 not in the language switcher (in_prod=false): bn-in, id, ro, uk
• 1 only builds HTML and not PDF, EPUB, etc: uk

I suggest that, by default, those not in the language switcher only build HTML. When they are added to the switcher, the non-HTML docs will also be built.

If we have a need to build non-HTML docs when in_prod=false, that should be possible by explicitly setting html_only=false.

This would only affect three languages at the moment, but would still save a significant amount of time.

The most recent full build of non-HTML took 23.5 hours:

2025-08-10 11:00 UTC | 3.14    | el       | 20m 17s        | Doc/ has changed
2025-08-10 11:20 UTC | 3.14    | en       | 25m 1s         | Doc/ has changed
2025-08-10 11:45 UTC | 3.14    | es       | 1h 25m 16s     | Doc/ has changed
2025-08-10 13:11 UTC | 3.14    | fr       | 28m 42s        | Doc/ has changed
2025-08-10 13:39 UTC | 3.14    | bn-in    | 24m 6s         | Doc/ has changed
2025-08-10 14:03 UTC | 3.14    | id       | 24m 36s        | Doc/ has changed
2025-08-10 14:28 UTC | 3.14    | it       | 23m 21s        | Doc/ has changed
2025-08-10 15:17 UTC | 3.14    | ko       | 44m 23s        | new translations
2025-08-10 16:01 UTC | 3.14    | pl       | 33m 1s         | new translations
2025-08-10 16:35 UTC | 3.14    | pt-br    | 51m 28s        | new translations
2025-08-10 17:26 UTC | 3.14    | ro       | 23m 13s        | new translations
2025-08-10 17:49 UTC | 3.14    | tr       | 1h 11m 56s     | Doc/ has changed
2025-08-10 19:01 UTC | 3.14    | zh-cn    | 1h 8m 46s      | new translations
2025-08-10 20:10 UTC | 3.14    | zh-tw    | 32m 9s         | Doc/ has changed
2025-08-10 20:42 UTC | 3.13    | el       | 19m 37s        | Doc/ has changed
2025-08-10 21:02 UTC | 3.13    | en       | 22m 3s         | Doc/ has changed
2025-08-10 21:24 UTC | 3.13    | es       | 1h 22m 14s     | Doc/ has changed
2025-08-10 22:46 UTC | 3.13    | fr       | 25m 36s        | Doc/ has changed
2025-08-10 23:12 UTC | 3.13    | bn-in    | 22m 22s        | Doc/ has changed
2025-08-10 23:34 UTC | 3.13    | id       | 21m 20s        | Doc/ has changed
2025-08-10 23:55 UTC | 3.13    | it       | 25m 56s        | Doc/ has changed
2025-08-11 00:45 UTC | 3.13    | ko       | 40m 5s         | new translations
2025-08-11 01:26 UTC | 3.13    | pl       | 27m 23s        | new translations
2025-08-11 01:53 UTC | 3.13    | pt-br    | 45m 40s        | new translations
2025-08-11 02:39 UTC | 3.13    | ro       | 22m 37s        | new translations
2025-08-11 03:01 UTC | 3.13    | tr       | 1h 7m 14s      | Doc/ has changed
2025-08-11 04:08 UTC | 3.13    | zh-cn    | 48m 48s        | new translations
2025-08-11 04:57 UTC | 3.13    | zh-tw    | 39m 53s        | Doc/ has changed
2025-08-11 05:40 UTC | --FULL- | -BUILD-- | 23h 33m 2s     | -----------

Of which, the non-prod + non-HTML ones took some 2h 18m:

2025-08-10 13:39 UTC | 3.14    | bn-in    | 24m 6s         | Doc/ has changed
2025-08-10 14:03 UTC | 3.14    | id       | 24m 36s        | Doc/ has changed
2025-08-10 17:26 UTC | 3.14    | ro       | 23m 13s        | new translations
2025-08-10 23:12 UTC | 3.13    | bn-in    | 22m 22s        | Doc/ has changed
2025-08-10 23:34 UTC | 3.13    | id       | 21m 20s        | Doc/ has changed
2025-08-11 02:39 UTC | 3.13    | ro       | 22m 37s        | new translations

Which is about 10% of the total.