Propagate training flag to FlowMatching Integrator

[han-ol]

Currently, dropout is ignored in FlowMatching.
I confirmed that the corresponding subnet_kwargs is propagated correctly to the subnet constructor. Nevertheless, dropout has no effect on training.

The Integrator and its subnet needs to receive a training=True flag to turn on dropout at training time.

[stefanradev93]

@LarsKue Should we provide a hot fix or will you address this soon with the integrators refactor?

[LarsKue]

Will be addressed with the refactor.

[paul-buerkner]

@LarsKue Is this issue solved already?

[LarsKue]

Fixed by #300