feat: Add combinatorial auction cutover logic

[mrnaveira]

Problem

We recently started implementing combinatorial auctions in the autopilot [1][2].

Right now the use of the new combinatorial auction logic is controlled by the max_winners_per_auction configuration parameter. If it's greater than 1 the autopilot will use combinatorial auctions.

But the solver team requested to be able to enable the use of combinatorial auctions based on a cutover timestamp. So when the configured cutover timestamp arrives, the autopilot should automatically switch to the combinatorial auctions regardless of the max_winners_per_auction value.

Suggested solution

The purpose of this task is to implement the required cutover logic in the autopilot:

• New configuration variable combinatorial_auctions_cutover in the autopilot
• Decouple the current selection of combinatorial auction logic from the max_winners_per_auction variable. Instead, check that the auction deadline is greater that the combinatorial_auctions_cutover.

For reference, we recently implemented a similar cutover logic in the driver (#3340) for a different feature

[MartinquaXD]

Implemented in #3423