test: gate packaged mobile Find Work journey (Closes #981)

frontend/dashboard.js

@@ -5678,9 +5678,10 @@
   });
 
   qs('#confirm-find-work-estimates').addEventListener('click', async event => {
-    event.currentTarget.disabled = true;
+    const button = event.currentTarget;
+    button.disabled = true;
     const outcome = await batchFindWork.run(findWorkController.selectedItems(), findWorkEstimateValues());
-    event.currentTarget.disabled = false;
+    button.disabled = false;
     if (outcome.status === 'estimates-required') {
       const first = outcome.invalid[0];
       document.querySelector('[data-find-work-estimate="' + CSS.escape(first) + '"]')?.focus();