remove unused device-message, avoid unneeded translations

res/values/strings.xml

@@ -695,9 +695,5 @@
 
 
     <!-- android specific strings, developers: please take care to remove strings that are no longer used! -->
-    <!-- this message is shown in the device chat, starting in version 1.6, it should explain the need for the permanent-notifiation and also use the same wording as used there (see "Background connection enabled") -->
-    <string name="device_talk_background_connection_android">You may already have noticed, that there is a hint \"Background connection enabled\" shown by the system.\n\n👉 The hint normally prevents the operating system from killing the connection between Delta Chat and your server.\n\n👉 If the hint disappears without any action on your part, the connection has probably been killed anyway.\nIf you think this is weird, we totally agree - but many manufacturers do exactly that. The site https://dontkillmyapp.com shows some workarounds.\n\nHowever, we are happy that we could improve the receiving of messages in background with this change and could fulfil the requests of many users - thanks for reporting 🤗</string>
-    <string name="device_talk_background_connection2_android">You can now enable and disabled the \"Background connection\" as needed at \"Settings / Notifications\".</string>
-
 
 </resources>

src/org/thoughtcrime/securesms/ConversationListActivity.java

@@ -87,11 +87,6 @@ public class ConversationListActivity extends PassphraseRequiredActionBarActivit
 
     // add welcome message
     dcContext.updateDeviceChats();
-    if (dcContext.wasDeviceMsgEverAdded("update1.6.0-h")) {
-      DcMsg msg = new DcMsg(dcContext, DcMsg.DC_MSG_TEXT);
-      msg.setText(getString(R.string.device_talk_background_connection2_android));
-      dcContext.addDeviceMsg("update1.8.0-a", msg);
-    }
 
     setContentView(R.layout.conversation_list_activity);