Decrease funding_sat

[matevz]

The current funding_sat minimum amount for opening a channel is 200,000 sats which roughly equals to $200 these days. This amount is relatively high for the newcomers or even those running LN node themselves and want to play around with it. I suggest to reduce this amount to something more reasonable like 10,000 sats (CLN default) or 20,000 sats (LND default) or even better - remove this check locally and let the target LN node decide.

Related: #7169 (comment)