Increase trampoline `cltv_expiry_delta`

[t-bast]

Once we're confident that enough (all?) wallets have upgraded to a version that includes #635, we can increase the trampoline cltv_expiry_delta in our wallet context. That gives more time to the trampoline node to wake-up the wallet when it needs to settle an HTLC, thus reducing the frequency of cases where the trampoline node must force-close because it couldn't settle an HTLC that is going to expire soon.