Update Japanese translation (and English translation file) for JavaScript (#2538)

* Update English translation file for JavaScript

* Update Japanese translation for JavaScript

app/assets/javascripts/components/locales/en.jsx

@@ -25,7 +25,6 @@ const en = {
   "account.unfollow": "Unfollow",
   "account.unmute": "Unmute @{name}",
   "boost_modal.combo": "You can press {combo} to skip this next time",
-  "column_back_button.label": "Back",
   "column.blocks": "Blocked users",
   "column.community": "Local timeline",
   "column.favourites": "Favourites",
@@ -37,6 +36,7 @@ const en = {
   "column_back_button.label": "Back",
   "column_subheading.navigation": "Navigation",
   "column_subheading.settings": "Settings",
+  "compose_form.lock_disclaimer": "Your account is not {locked}. Anyone can follow you to view your follower-only posts.",
   "compose_form.lock_disclaimer.lock": "locked",
   "compose_form.placeholder": "What is on your mind?",
   "compose_form.privacy_disclaimer": "Your private status will be delivered to mentioned users on {domains}. Do you trust {domainsCount, plural, one {that server} other {those servers}}? Post privacy only works on Mastodon instances. If {domains} {domainsCount, plural, one {is not a Mastodon instance} other {are not Mastodon instances}}, there will be no indication that your post is private, and it may be boosted or otherwise made visible to unintended recipients.",