Fix order of thermal flexibility provision

[danielfeismann]

at the moment thermal storages are only used after the thermal house has reached it's upper temp boundary.

The order should be:

• heat up house till target temperature
• heat up thermal storage (either in any case or only if surplus energy is available -> to be discussed)
• overheat the house till upper temperature boundary

[danielfeismann]

Update: Behaviour checked for thermal grids under the control of energyManagement.

• heat up house till upper temperature boundary (using surplus energy from pv)
• heat up thermal storage

Possible change: Only heat up house till target temperature, heat up thermal storage (in any case, not only for surplus energy), overheat house till upper temperature in case of surplus energy.

Check for thermal grids without Em needs to be done

[danielfeismann]

Please check if this is still valid after #827 will be completed