Core/LootMgr: Fix GCC warning
Revert "Core/AuctionHouse: Delete expired auctions at startup."

This reverts commit a92038feaf440abe797ee4b0344612b6176e43a8 which caused items of expired auctions not being mailed back to the owner and leaving those items in item_instance table.

Please refer to the forum for steps to verify the integrity of your database and remove old unneeded rows in item_instance table.

Fixes #12699