[PM-28071] add prod test domain for phishing detection (#17450)

apps/browser/src/dirt/phishing-detection/services/phishing-data.service.ts

@@ -58,6 +58,7 @@ export class PhishingDataService {
         new Set(
           (state?.domains?.filter((line) => line.trim().length > 0) ?? []).concat(
             this._testDomains,
+            "phishing.testcategory.com", // Included for QA to test in prod
           ),
         ),
     ),