i18n: remove bad translations

Change-Id: I77c33f92216ed79b2bb29d5f502dcdd298bf5de8

ring-android/app/src/main/res/values-en-rGB/strings_account.xml

-<?xml version='1.0' encoding='UTF-8'?>
-<resources>
-  <!--Strings related to account edition screen-->
-  <!--Strings related to account creation-->
-  <!--Strings related to account deletion-->
-  <!--AccountManagementFragment-->
-  <!--Basic Details-->
-  <!--Audio Details-->
-  <string name="account_audio_label">Audio</string>
-  <string name="account_ringtone_label">Ringtones</string>
-  <!--Video Details-->
-  <string name="account_video_label">Video</string>
-  <!--Advanced Details-->
-  <!--Security Details-->
-  <!--SRTP Details-->
-  <!--SIP-->
-  <!--TLS Details-->
-  <!--restore/backup-->
-  <!--Name registration-->
-  <!--Create account-->
-  <!--Edit profile-->
-  <!--Devices-->
-</resources>

ring-android/app/src/main/res/values-en-rGB/strings_preferences.xml

-<?xml version='1.0' encoding='UTF-8'?>
-<resources>
-  <string name="pref_category_video">Video</string>
-</resources>

ring-android/app/src/main/res/values-en-rUS/strings_account.xml

-<?xml version='1.0' encoding='UTF-8'?>
-<resources>
-  <!--Strings related to account edition screen-->
-  <!--Strings related to account creation-->
-  <!--Strings related to account deletion-->
-  <!--AccountManagementFragment-->
-  <!--Basic Details-->
-  <!--Audio Details-->
-  <string name="account_ringtone_label">铃声</string>
-  <!--Video Details-->
-  <string name="account_video_label">视频</string>
-  <!--Advanced Details-->
-  <!--Security Details-->
-  <!--SRTP Details-->
-  <!--SIP-->
-  <!--TLS Details-->
-  <!--restore/backup-->
-  <!--Name registration-->
-  <!--Create account-->
-  <!--Edit profile-->
-  <!--Devices-->
-</resources>

ring-android/app/src/main/res/values-en-rUS/strings_preferences.xml

-<?xml version='1.0' encoding='UTF-8'?>
-<resources>
-  <string name="pref_category_video">Video</string>
-</resources>