to verify node behaviour and debug log when launching bitcoind in these cases:
1. `bitcoind` with no -asmap arg, using /16 prefix for IP bucketing
2. `bitcoind -asmap=<relative path>`, using the unit test skeleton asmap
3. `bitcoind -asmap/-asmap=` with no file specified, using the default asmap
4. `bitcoind -asmap` with no file specified, and a missing default asmap file
The tests are order-independent. The slowest test (missing default asmap file)
is placed last.