graph: use UNION for isPublicNode query

In this commit we updated the IsPublicV1Node query to use UNION
instead of OR, since sqlite struggles to efficiently use
multiple indexes in a single query involving OR conditions across
different columns.

We use UNION ALL since the query doesn't care about duplicates.

Author: Abdulkbk

sqldb/sqlc/graph.sql.go

@@ -56,7 +56,7 @@ LIMIT $3;
 SELECT EXISTS (
     SELECT 1
     FROM graph_channels c
-    JOIN graph_nodes n ON n.id = c.node_id_1 OR n.id = c.node_id_2
+    JOIN graph_nodes n ON n.id = c.node_id_1
     -- NOTE: we hard-code the version here since the clauses
     -- here that determine if a node is public is specific
     -- to the V1 gossip protocol. In V1, a node is public
@@ -68,6 +68,13 @@ SELECT EXISTS (
     WHERE c.version = 1
       AND c.bitcoin_1_signature IS NOT NULL
       AND n.pub_key = $1
+    UNION ALL
+    SELECT 1
+    FROM graph_channels c
+    JOIN graph_nodes n ON n.id = c.node_id_2
+    WHERE c.version = 1
+      AND c.bitcoin_1_signature IS NOT NULL
+      AND n.pub_key = $1
 );
 
 -- name: DeleteUnconnectedNodes :many