improvement(performance): remove unused source/target indices, add index on snapshot id (#1603)

Author: waleedlatif1

packages/db/migrations/0098_thick_prima.sql

@@ -0,0 +1,3 @@
+DROP INDEX "workflow_edges_source_block_idx";--> statement-breakpoint
+DROP INDEX "workflow_edges_target_block_idx";--> statement-breakpoint
+CREATE INDEX "workflow_execution_logs_state_snapshot_id_idx" ON "workflow_execution_logs" USING btree ("state_snapshot_id");