Moving window length for fwd. temperature approximation can exceed snapshot length

[amos-schledorn]

Problem

When approximating central heating forward temperatures, ambient temperature is smoothed by a moving average of, per default, rolling_window_ambient_temperature=72[h].
If the snapshot length is lower than 72 hours, xarray runs into an error when calculating the moving average.
(reported by @bobbyxng )

Hot fix

Modify rolling window length in config.

Long-term fix

• If this happens, throw a warning
• Clip the rolling window length to the snapshot length
• A warning rather than an error should be fine since we expect no user to make runs with snapshot length below rolling window length in production but rather for testing (@fneum)