entity-manager: not throw in createAddObjectMethod

We do not throw at the other call site in entity_manager.cpp.

Looked at all 3 places where there's a 'catch'

```
$ rg catch src/entity_manager/
src/entity_manager/dbus_interface.cpp
39:    catch (std::exception& e)

src/entity_manager/configuration.hpp
39:    catch (const std::out_of_range&)

src/entity_manager/expression.cpp
100:            catch (const std::invalid_argument&)
```

but none of these would catch this exception.

Remove the throw here to align with the other call site and prevent
process termination.

Tested: Inspection only.

Change-Id: I90d70f3f59237b32fbf102c970cc1ed7de94e34c
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/src/entity_manager/dbus_interface.cpp b/src/entity_manager/dbus_interface.cpp
index cea5d42..3ae698c 100644
--- a/src/entity_manager/dbus_interface.cpp
+++ b/src/entity_manager/dbus_interface.cpp
@@ -344,7 +344,6 @@
             if (!writeJsonFiles(systemConfiguration))
             {
                 std::cerr << "Error writing json files\n";
-                throw DBusInternalError();
             }
             std::string dbusName = *name;