Change EVCS behaviour in case of V2G and at least one charging EV

[danielfeismann]

In the following PR, the question was raised whether it is the preferred option to stop discharging an EV when at least one EV needs to be charged at the charging station.

• [ ] Discuss the preferred behaviour

• [ ] Adapt if necessary

          Don't agree here. If an evcs at some house is in v2g-mode and a second car arives with little SoC both, charging and discharging can be fine.
  

Originally posted by @danielfeismann in https://github.com/ie3-institute/simona/pull/714#discussion_r1482601276