Update standing losses of thermal energy storage

[amos-schledorn]

Currently, we use the parameter tes_tau to derive standing losses for thermal energy storage (both TTES and PTES after #1444 has been merged).

I'd suggest updating this with data from the DEA technology catalogue (which assumes there not being a reason to prefer tes_tau over DEA data, @nworbmot ?)

@TomKae00 This update would require adding the data the respective data to technology-data (copy-paste for TTES and deriving energetic PTES standing losses from temperature losses [K/day] for PTES) and then updating PyPSA-Eur after @nworbmot has given his okay to replace tes_tau.