Validate that the default sequence name is present in the database at startup

[JonasKellerer]

In #471 it was raised the issue, that the default sequence name defined in the database config does not have to be a valid sequence name. Add a check to this during startup of the database, so we can be sure in the queries, that the default sequence name is always present. Then remove the check in insertion_contains.cpp

[Taepper]

It should be resolved with #454 . We will verify after and close accordingly