graph/db+sqldb: improve performance of chan update sql migration

This commit simplifies insertChanEdgePolicyMig. Much of the logic can be
removed given that this method is only used in the context of the graph
SQL migration.

This should improve the performance of the migration quite a lot since
it removes the extra GetChannelAndNodesBySCID call.

sqldb/sqlc/graph.sql.go

@@ -2304,29 +2304,6 @@ func (q *Queries) HighestSCID(ctx context.Context, version int16) ([]byte, error
 	return scid, err
 }
 
-const insertChanPolicyExtraType = `-- name: InsertChanPolicyExtraType :exec
-/* ─────────────────────────────────────────────
-   graph_channel_policy_extra_types table queries
-   ─────────────────────────────────────────────
-*/
-
-INSERT INTO graph_channel_policy_extra_types (
-    channel_policy_id, type, value
-)
-VALUES ($1, $2, $3)
-`
-
-type InsertChanPolicyExtraTypeParams struct {
-	ChannelPolicyID int64
-	Type            int64
-	Value           []byte
-}
-
-func (q *Queries) InsertChanPolicyExtraType(ctx context.Context, arg InsertChanPolicyExtraTypeParams) error {
-	_, err := q.db.ExecContext(ctx, insertChanPolicyExtraType, arg.ChannelPolicyID, arg.Type, arg.Value)
-	return err
-}
-
 const insertChannelFeature = `-- name: InsertChannelFeature :exec
 /* ─────────────────────────────────────────────
    graph_channel_features table queries
@@ -3429,6 +3406,33 @@ func (q *Queries) ListNodesPaginated(ctx context.Context, arg ListNodesPaginated
 	return items, nil
 }
 
+const upsertChanPolicyExtraType = `-- name: UpsertChanPolicyExtraType :exec
+/* ─────────────────────────────────────────────
+   graph_channel_policy_extra_types table queries
+   ─────────────────────────────────────────────
+*/
+
+INSERT INTO graph_channel_policy_extra_types (
+    channel_policy_id, type, value
+)
+VALUES ($1, $2, $3)
+ON CONFLICT (channel_policy_id, type)
+    -- If a conflict occurs on channel_policy_id and type, then we update the
+    -- value.
+    DO UPDATE SET value = EXCLUDED.value
+`
+
+type UpsertChanPolicyExtraTypeParams struct {
+	ChannelPolicyID int64
+	Type            int64
+	Value           []byte
+}
+
+func (q *Queries) UpsertChanPolicyExtraType(ctx context.Context, arg UpsertChanPolicyExtraTypeParams) error {
+	_, err := q.db.ExecContext(ctx, upsertChanPolicyExtraType, arg.ChannelPolicyID, arg.Type, arg.Value)
+	return err
+}
+
 const upsertChannelExtraType = `-- name: UpsertChannelExtraType :exec
 /* ─────────────────────────────────────────────
    graph_channel_extra_types table queries