trampoline: micropayments less likely to proceed with high fee levels

[bitromortac]

I tested some micropayments with 100 sat (with the reintroduced global fee level #7623) and it often happens that trampoline routes are rejected due to

electrum/electrum/lnrouter.py

Line 166 in 9bbf92b

if 100 * fee_msat <= payment_amount_msat:

with high trampoline fee levels (e.g., fee level 4) that results in >=1% fees. I'd suggest to accept a higher whitelisting of fees, what would be a good value, 10 sat instead of 5 sat? There's also the issue of making these values user configurable #7622. The 1% value could also be lowered a bit perhaps.