Move every db.Prepare to sqlutil.Statementlist, remove trace driver (#3026)

Doesn't buy us much, but makes everything a bit more consistent.

Also removes the SQL trace driver, as it is unused and the output is
hard to read anyway.

internal/sqlutil/sqlite_cgo.go

@@ -4,7 +4,6 @@
 package sqlutil
 
 import (
-	"github.com/mattn/go-sqlite3"
 	_ "github.com/mattn/go-sqlite3"
 )
 
@@ -13,7 +12,3 @@ const SQLITE_DRIVER_NAME = "sqlite3"
 func sqliteDSNExtension(dsn string) string {
 	return dsn
 }
-
-func sqliteDriver() *sqlite3.SQLiteDriver {
-	return &sqlite3.SQLiteDriver{}
-}