sqldb+go.mod: update sqldb test methods

Update the test methods to take a `testing.TB` param instead of a
`*testing.T` so that the test functions can be used for all the graph's
tests including benchmark tests.

We also add a temporary replace so that we can make use of these changes
and also since we will soon be adding graph related schemas and queries
in this submodule that we'll want to have access to.

go.mod

@@ -199,6 +199,10 @@ require (
 	sigs.k8s.io/yaml v1.2.0 // indirect
 )
 
+// TODO(elle): remove once all the schemas and queries for the graph
+// store have been included in a tagged sqldb version.
+replace github.com/lightningnetwork/lnd/sqldb => ./sqldb
+
 // This replace is for https://github.com/advisories/GHSA-25xm-hr59-7c27
 replace github.com/ulikunitz/xz => github.com/ulikunitz/xz v0.5.11