core_tests: bump default test fee to 0.02 monero
core_tests: bump default test fee to 0.02 monero

The current monero consensus uses 0.01 per kB fees, so use enough
for 2 kB transactions for now. It'll probably have to be either
bumped further or changed to calculate the proper fee.

ranok/bitmonero,eiabea/bitmonero,eiabea/bitmonero,ranok/bitmonero,ranok/bitmonero,ranok/bitmonero,ranok/bitmonero,eiabea/bitmonero,ranok/bitmonero,eiabea/bitmonero,eiabea/bitmonero,eiabea/bitmonero