Change pause logic in rebalancer to a enum state

[Art3miX]

https://github.com/timewave-computer/valence-services/pull/1#discussion_r1367071728

enum RebalancerState {
    Active,
    Paused(String), // paused by?
}

[uditvira]

We now have different logic for pausing/resuming due to the fee required to unpause. Closing for now