fix(electron): remove all migration code in electron (#6969)

The migration code import blocksuite in the dependency tree and prevent affine from running because electron's helper process tries to run browser only code that is part of the side effect of `@blocksuite/blocks`.

![image.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/T2klNLEk0wxLh4NRDzhk/53da3972-7433-4631-b8c2-d3e322066c7d.png)

[The side effect free trick in esbuild config](https://github.com/toeverything/AFFiNE/pull/6415)  does not clean up these - not sure why.

It has been already 6 month since we introduced the migration code in DB.
Instead of finding out the real root cause, I think may be better to remove the migration code completely so that no blocksuite code will be in the import paths in helper.js.

![image.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/T2klNLEk0wxLh4NRDzhk/3b03522a-2a25-4bdb-8287-86a6b94623e1.png)

packages/frontend/electron/test/db/migration.spec.ts

@@ -1,86 +0,0 @@
-import path from 'node:path';
-
-import { SqliteConnection } from '@affine/native';
-import { removeWithRetry } from '@affine-test/kit/utils/utils';
-import {
-  afterAll,
-  afterEach,
-  beforeAll,
-  describe,
-  expect,
-  it,
-  vi,
-} from 'vitest';
-import { applyUpdate, Doc as YDoc } from 'yjs';
-
-const tmpDir = path.join(__dirname, 'tmp');
-const testDBFilePath = path.resolve(__dirname, 'old-db.affine');
-
-const appDataPath = path.join(tmpDir, 'app-data');
-
-beforeAll(() => {
-  vi.doMock('@affine/electron/helper/main-rpc', () => ({
-    mainRPC: {
-      getPath: async () => appDataPath,
-      channel: {
-        on: () => {},
-        send: () => {},
-      },
-    },
-  }));
-});
-
-afterEach(async () => {
-  await removeWithRetry(tmpDir);
-});
-
-afterAll(() => {
-  vi.doUnmock('@affine/electron/helper/main-rpc');
-});
-
-describe('migrateToSubdocAndReplaceDatabase', () => {
-  it('should migrate and replace the database', async () => {
-    const { copyToTemp, migrateToSubdocAndReplaceDatabase } = await import(
-      '@affine/electron/helper/db/migration'
-    );
-    const copiedDbFilePath = await copyToTemp(testDBFilePath);
-    await migrateToSubdocAndReplaceDatabase(copiedDbFilePath);
-
-    const db = new SqliteConnection(copiedDbFilePath);
-    await db.connect();
-
-    // check if db has two rows, one for root doc and one for subdoc
-    const rows = await db.getAllUpdates();
-    expect(rows.length).toBe(2);
-
-    const rootUpdate = rows.find(row => row.docId === undefined)!.data;
-    const subdocUpdate = rows.find(row => row.docId !== undefined)!.data;
-
-    expect(rootUpdate).toBeDefined();
-    expect(subdocUpdate).toBeDefined();
-
-    // apply updates
-    const rootDoc = new YDoc();
-    applyUpdate(rootDoc, rootUpdate);
-
-    // check if root doc has one subdoc
-    expect(rootDoc.subdocs.size).toBe(1);
-
-    // populates subdoc
-    applyUpdate(rootDoc.subdocs.values().next().value, subdocUpdate);
-
-    // check if root doc's meta is correct
-    const meta = rootDoc.getMap('meta').toJSON();
-    expect(meta.workspaceVersion).toBe(1);
-    expect(meta.name).toBe('hiw');
-    expect(meta.pages.length).toBe(1);
-    const pageMeta = meta.pages[0];
-    expect(pageMeta.title).toBe('Welcome to AFFiNEd');
-
-    // get the subdoc through id
-    const subDoc = rootDoc.getMap('spaces').get(pageMeta.id) as YDoc;
-    expect(subDoc).toEqual(rootDoc.subdocs.values().next().value);
-
-    await db.close();
-  });
-});