move string to donottranslate.xml and fix nits

app/src/main/java/org/schabi/newpipe/download/DownloadDialog.java

@@ -566,8 +566,6 @@ public class DownloadDialog extends DialogFragment
     }
 
     private void onItemSelectedSetFileName() {
-        final String setSubtitleLanguageCode = subtitleStreamsAdapter.getItem(selectedSubtitleIndex)
-                .getLanguageTag();
         final String fileName = FilenameUtils.createFilename(getContext(),
                 currentInfo.getName());
         switch (dialogBinding.videoAudioGroup.getCheckedRadioButtonId()) {
@@ -576,7 +574,9 @@ public class DownloadDialog extends DialogFragment
                 dialogBinding.fileName.setText(fileName);
                 break;
             case R.id.subtitle_button:
-                dialogBinding.fileName.setText(fileName + getString(
+                final String setSubtitleLanguageCode = subtitleStreamsAdapter
+                        .getItem(selectedSubtitleIndex).getLanguageTag();
+                dialogBinding.fileName.setText(getString(
                         R.string.caption_file_name, fileName, setSubtitleLanguageCode));
                 break;
         }

app/src/main/res/values/donottranslate.xml

@@ -27,4 +27,5 @@
     <string name="soundcloud">SoundCloud</string>
     <string name="preferred_open_action_share_menu_title">@string/app_name</string>
     <string name="leakcanary">LeakCanary</string>
+    <string name="caption_file_name">%1$s-%2$s</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -452,7 +452,6 @@
     <string name="resize_zoom">Zoom</string>
     <string name="caption_auto_generated">Auto-generated</string>
     <!-- Caption Settings -->
-    <string name="caption_file_name">%1$s-%2$s</string>
     <string name="caption_setting_title">Captions</string>
     <string name="caption_setting_description">Modify player caption text scale and background styles. Requires app restart to take effect</string>
     <!-- Debug Settings -->