fix(dtl): bug with shutoff logic (#4240)

Fixes a bug with the DTL's shutoff block logic.

.changeset/stale-experts-roll.md

+---
+'@eth-optimism/data-transport-layer': patch
+---
+
+Fixes a bug with the DTL shutoff block logic

packages/data-transport-layer/src/services/l1-ingestion/service.ts

@@ -228,7 +228,7 @@ export class L1IngestionService extends BaseService<L1IngestionServiceOptions> {
         )
 
         // Don't sync beyond the shutoff block!
-        if (this.options.l1SyncShutoffBlock !== undefined) {
+        if (Number.isInteger(this.options.l1SyncShutoffBlock)) {
           targetL1Block = Math.min(
             targetL1Block,
             this.options.l1SyncShutoffBlock