Simplify RBAPINN, SelfAdaptivePINN, CompetitivePINN logic

[dario-coscia]

Hi! I open this PR for keeping track of some updates in three solvers.
RBAPINN, SelfAdaptivePINN => here we simplify by movign everything insive optimization_cycle instead of having it in _optimization_cyle (this method should be untouched)
CompetitivePINN, SelfAdaptivePINN => here we can remove the configure_optimizer method since is already done

[dario-coscia]

@GiovanniCanali this now becomes high priority fix, in order to procede faster with #618