With go 1.17 a change to the build flags was implemented:
https://go.googlesource.com/proposal/+/master/design/draft-gobuild.md
The formatter now automatically adds the forward-compatible build tag
format and the linter checks for them, so we need to include them in our
code.
In this commit, we modify the logic within RegisterSpendNtfn for the
BtcdNotifier to account for the recent changes made to the TxNotifier.
Since it is now able to handle spend notification registration and
dispatch, we can bypass all the current logic within the
BtcdNotifier and interact directly with the TxNotifier instead.
The most notable change is that now we'll only attempt a historical
rescan if the TxNotifier tells us so.
