Exclude erased messages from backup

Co-authored-by: trevor-signal <131492920+trevor-signal@users.noreply.github.com>

ts/services/backups/export.preload.ts

@@ -1745,6 +1745,8 @@ export class BackupExportStream extends Readable {
     } else if (message.pollTerminateNotification) {
       // TODO (DESKTOP-9282)
       return undefined;
+    } else if (message.isErased) {
+      return undefined;
     } else {
       result.standardMessage = await this.#toStandardMessage({
         message,

ts/test-electron/backup/bubble_test.preload.ts

@@ -603,6 +603,28 @@ describe('backup/bubble messages', () => {
       []
     );
   });
+  it('drops erased messages', async () => {
+    await asymmetricRoundtripHarness(
+      [
+        {
+          conversationId: gv1.id,
+          id: generateGuid(),
+          type: 'incoming',
+          received_at: 3,
+          received_at_ms: 3,
+          isErased: true,
+          sent_at: 3,
+          timestamp: 3,
+          sourceServiceId: CONTACT_A,
+          body: 'd',
+          readStatus: ReadStatus.Unread,
+          seenStatus: SeenStatus.Unseen,
+          unidentifiedDeliveryReceived: true,
+        },
+      ],
+      []
+    );
+  });
 
   it('drops messages that expire soon', async () => {
     await asymmetricRoundtripHarness(