[account.cpp] refactor gnc_account_get_map_entry

Have comprehensive tests in a5d101d1b

libgnucash/engine/Account.cpp

@@ -6021,23 +6021,10 @@ gnc_account_imap_get_info (Account *acc, const char *category)
 gchar *
 gnc_account_get_map_entry (Account *acc, const char *head, const char *category)
 {
-    GValue v = G_VALUE_INIT;
-    gchar *text = NULL;
-    std::vector<std::string> path {head};
     if (category)
-        path.emplace_back (category);
-    if (qof_instance_has_path_slot (QOF_INSTANCE (acc), path))
-    {
-        qof_instance_get_path_kvp (QOF_INSTANCE (acc), &v, path);
-        if (G_VALUE_HOLDS_STRING (&v))
-        {
-            gchar const *string;
-            string = g_value_get_string (&v);
-            text = g_strdup (string);
-        }
-    }
-    g_value_unset (&v);
-    return text;
+        return get_kvp_string_path (acc, {head, category});
+    else
+        return get_kvp_string_path (acc, {head});
 }