Fix seq window derivation

[LEAFERx]

Background

• Previously, when seq window of epoch E passed, derivation will create all empty batches belongs to E and the first empty batch belongs to E+1, even if seq window of epoch E+1 haven't passed yet
• Since sequencer will only create l1 oracle update transaction at the first batch of an epoch, this prevents them being created forever once seq window passed

Core changes

• Changed derivation pipeline behavior so that it creates empty batches for an epoch only when its seq window passed entirely, so sequencer will still have a chance to create l1 oracle update transactions