The first commit logs a message for each configured wallet if `-disablewallet` is set:
```
bitcoind -printtoconsole -regtest -disablewallet -wallet=foo -wallet=bar
...
WalletParameterInteraction: parameter interaction: -disablewallet -> ignoring -wallet=foo
WalletParameterInteraction: parameter interaction: -disablewallet -> ignoring -wallet=bar
```
It also moves up the `-disablewallet` check which avoids the unnecessary `-wallet` soft set.

The second commit fixes the default value of `-disablewallet`, currently the value is correct, but it should use `DEFAULT_DISABLE_WALLET`.

The third commit can be dropped or squashed, just took the opportunity to fix the coding style there.

ninja all check check-functional
bitcoind -datadir=[testnetdirwithextrawallet] -disablewallet -wallet=testing