Use Math.floor when calcNextEventTick for charging entities

[danielfeismann]

resolves #1256

[sebastian-peter]

Thanks for the discussion and the initiative.

Found some more examples that we should adapt at the same time:

simona/src/main/scala/edu/ie3/simona/model/thermal/CylindricalThermalStorage.scala

Lines 108 to 109 in 9c80601

	val duration = (maxEnergyThreshold - updatedEnergy) / qDot
	val durationInTicks = Math.round(duration.toSeconds)

simona/src/main/scala/edu/ie3/simona/model/thermal/CylindricalThermalStorage.scala

Lines 115 to 116 in 9c80601

	val duration = updatedEnergy / qDot * (-1)
	val durationInTicks = Math.round(duration.toSeconds)

simona/src/main/scala/edu/ie3/simona/model/thermal/ThermalHouse.scala

Lines 339 to 342 in 9c80601

	val duration = Math.round(
	(flexibleEnergy / (qDot * math.signum(qDot.toWatts))).toSeconds
	)
	Some(tick + duration)

[sebastian-peter]

Sorry, didn't realize that many tests needed to be adapted. Thanks though