Update backup benchmark timing

ts/services/backups/index.ts

@@ -302,7 +302,7 @@ export class BackupsService {
 
     log.info(`importBackup: starting ${backupType}...`);
     this.isRunning = 'import';
-
+    const importStart = Date.now();
     try {
       const importStream = await BackupImportStream.create(backupType);
       if (backupType === BackupType.Ciphertext) {
@@ -390,7 +390,9 @@ export class BackupsService {
       this.isRunning = false;
       window.IPC.stopTrackingQueryStats({ epochName: 'Backup Import' });
       if (window.SignalCI) {
-        window.SignalCI.handleEvent('backupImportComplete', null);
+        window.SignalCI.handleEvent('backupImportComplete', {
+          duration: Date.now() - importStart,
+        });
       }
     }
   }

ts/test-mock/benchmarks/backup_bench.ts

@@ -19,19 +19,15 @@ Bootstrap.benchmark(async (bootstrap: Bootstrap): Promise<void> => {
 
   await server.storeBackupOnCdn(backupId, backupStream);
 
-  const importStart = Date.now();
-
   const app = await bootstrap.link();
-  await app.waitForBackupImportComplete();
-
-  const importEnd = Date.now();
+  const { duration: importDuration } = await app.waitForBackupImportComplete();
 
   const exportStart = Date.now();
   await app.uploadBackup();
   const exportEnd = Date.now();
 
   console.log('run=%d info=%j', 0, {
-    importDuration: importEnd - importStart,
+    importDuration,
     exportDuration: exportEnd - exportStart,
   });
 });

ts/test-mock/playwright.ts

@@ -109,7 +109,7 @@ export class App extends EventEmitter {
     return this.waitForEvent('contactSync');
   }
 
-  public async waitForBackupImportComplete(): Promise<void> {
+  public async waitForBackupImportComplete(): Promise<{ duration: number }> {
     return this.waitForEvent('backupImportComplete');
   }