ChessGame: remove method getAccountGames
ChessGame: remove method getAccountGames

This method has been unused since 10c756269d (2011). We have no need
for it because chess games are scoped to (non-chess) game rounds.

smrealms/smr,smrealms/smr,smrealms/smr,hemberger/smr,hemberger/smr,hemberger/smr,hemberger/smr