Refactor to avoid trading once when stop trading is set to true, or KPI staking conditions are met

[jmoreira-valory]

As explained in #245, due to the current implementation of the trader, it requires significant refactor to skip directly to the RedeemRound when the Trader is started.

A quick solution was implement (on that PR) the fact that the trader must always execute the "full trading path" at least once (for the first period). Then it can skip trading.

This has the implication that the trader needs to through the full bet cycle at least once (even if disable_trading=true or staking KPI conditions are met), which will incur in making one mech request (and placing the bet if it deems it's profitable).