Fix uninitialized configuration values accessed when deleting expired auctions on startup

Valgrind log:
Conditional jump or move depends on uninitialised value(s)
 at : MailDraft::SendMailTo(Trinity::AutoPtr<Transaction, ACE_Thread_Mutex>&, MailReceiver const&, MailSender const&, MailCheckMask, unsigned int) (Mail.cpp:184)
 by : AuctionHouseMgr::SendAuctionSuccessfulMail(AuctionEntry*, Trinity::AutoPtr<Transaction, ACE_Thread_Mutex>&) (AuctionHouseMgr.cpp:184)
 by : AuctionHouseMgr::DeleteExpiredAuctionsAtStartup() (AuctionHouseMgr.cpp:776)
 by : World::SetInitialWorldSettings() (World.cpp:1612)
 by : Master::Run() (Master.cpp:169)
 by : main (Main.cpp:142)