Remove calling of WIP preview functionality

Author: koppor

src/main/java/org/jabref/preferences/JabRefPreferences.java

@@ -652,7 +652,7 @@ private JabRefPreferences() {
         defaults.put(VERSION_IGNORED_UPDATE, "");
 
         // preview
-        defaults.put(CYCLE_PREVIEW, "Preview;" + "bst/IEEEtran.bst;" + CitationStyle.DEFAULT);
+        defaults.put(CYCLE_PREVIEW, "Preview;" + CitationStyle.DEFAULT);
         defaults.put(CYCLE_PREVIEW_POS, 0);
         defaults.put(PREVIEW_PANEL_HEIGHT, 0.65);
         defaults.put(PREVIEW_AS_TAB, Boolean.FALSE);
@@ -1493,8 +1493,6 @@ public PreviewPreferences getPreviewPreferences() {
                                                    return CitationStyle.createCitationStyleFromFile(layout)
                                                                        .map(file -> (PreviewLayout) new CitationStylePreviewLayout(file))
                                                                        .orElse(null);
-                                               } else if (layout.endsWith(".bst")) {
-                                                   return new BstPreviewLayout(layout);
                                                } else {
                                                    return new TextBasedPreviewLayout(style, getLayoutFormatterPreferences(Globals.journalAbbreviationLoader));
                                                }