Update transifex language map

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

l10n/.tx/config

 [main]
 host = https://www.transifex.com
-lang_map = ja_JP: ja
+lang_map = bg_BG: bg, cs_CZ: cs, fi_FI: fi, hu_HU: hu, nb_NO: nb, sk_SK: sk, th_TH: th, ja_JP: ja
 
 [nextcloud.mail]
 file_filter = <lang>/mail.po