i18n: Drop empty, discontinued translations fr_FR, hr_HR, nb_NO

We dropped a while ago in Transifex because they were virtually empty,
and appeared to have been created by mistake:
  https://chat.zulip.org/#narrow/stream/58-translation/topic/language.20cleanup/near/1147119
presumably by people who actually wanted to be contributing to
`fr`, `hr`, or `no`.

They've stuck around in our tree, though, because `tools/tx-sync`
doesn't automatically remove old files.  Remove them now.
Done like so:

  $ rm static/translations/messages_*.json
  $ git checkout static/translations/messages_en.json
  $ tools/tx-pull

Two of the files have no translations at all -- they're identical
to an old version of `messages_en.json`:

  $ git diff 5282a37:static/translations/messages_en.json \
      HEAD:static/translations/messages_fr_FR.json

The third, `nb_NO`, has two translations, for the strings "Active" and
"(This user has been deactivated)".  Identical translations to each of
those are present today in `no`.

Author: gnprice

flow-typed/translations.js

@@ -80,10 +80,6 @@ declare module '../../static/translations/messages_fr.json' {
   declare export default {| [string]: string |};
 }
 
-declare module '../../static/translations/messages_fr_FR.json' {
-  declare export default {| [string]: string |};
-}
-
 declare module '../../static/translations/messages_gl.json' {
   declare export default {| [string]: string |};
 }
@@ -100,10 +96,6 @@ declare module '../../static/translations/messages_hr.json' {
   declare export default {| [string]: string |};
 }
 
-declare module '../../static/translations/messages_hr_HR.json' {
-  declare export default {| [string]: string |};
-}
-
 declare module '../../static/translations/messages_hu.json' {
   declare export default {| [string]: string |};
 }
@@ -140,10 +132,6 @@ declare module '../../static/translations/messages_my.json' {
   declare export default {| [string]: string |};
 }
 
-declare module '../../static/translations/messages_nb_NO.json' {
-  declare export default {| [string]: string |};
-}
-
 declare module '../../static/translations/messages_nl.json' {
   declare export default {| [string]: string |};
 }

src/i18n/messages.js

@@ -30,12 +30,10 @@ export default {
   fa: require('../../static/translations/messages_fa.json'),
   fi: require('../../static/translations/messages_fi.json'),
   fr: require('../../static/translations/messages_fr.json'),
-  'fr-FR': require('../../static/translations/messages_fr_FR.json'),
   gl: require('../../static/translations/messages_gl.json'),
   gu: require('../../static/translations/messages_gu.json'),
   hi: require('../../static/translations/messages_hi.json'),
   hr: require('../../static/translations/messages_hr.json'),
-  'hr-HR': require('../../static/translations/messages_hr_HR.json'),
   hu: require('../../static/translations/messages_hu.json'),
   id: require('../../static/translations/messages_id.json'),
   it: require('../../static/translations/messages_it.json'),