Tests fail because the database is not ready

Issue: When swapping to CarbonRunner my tests using MongoMemoryReplSet stop working

Reason: Not waiting for the database to be properly initialized.

Bad examples

Using an even number of replica sets

 replSet = await MongoMemoryReplSet.create({
      replSet: { count: 4 }, // 4-member replica set
  });

Add a wait as suggested in the tests of mongodb-memory-server. e.g.
```
await new Promise((resolve) => setTimeout(resolve, 2000));
```

Good solution

Use an odd number of replica sets

 replSet = await MongoMemoryReplSet.create({
      replSet: { count: 5 }, // 5-member replica set
  });

Wait for the database to initialize all replica sets


  const replicaCount = 5;

  async function waitUntilReady(uri, dbname) {
      let retries = 60;
      while (retries > 0) {
          retries -= 1;

          try {
              const cl = new MongoClient(uri);
              await cl.connect();
              const db = client.db(dbname);
              const admin = db.admin();
              const status = await admin.replSetGetStatus();
              const currentCount = status.members.filter(
                  (m) => m.stateStr === 'SECONDARY'
              ).length;

              if (currentCount !== replicaCount - 1) {
                  await new Promise((resolve) => setTimeout(resolve, 1000));
                  cl.close()
                  continue
              }

              cl.close()
              return
          } catch (err) {
              console.error(err)
              await new Promise((resolve) => setTimeout(resolve, 1000));
          }
      }
  }


  beforeAll(async () => {
      replSet = await MongoMemoryReplSet.create({
          replSet: { count: replicaCount }, // 5-member replica set
      });

      const dbname = 'testdb';

      await replSet.waitUntilRunning();

      const uri = replSet.getUri();
      await waitUntilReady(uri, dbname)

      const cl = new MongoClient(uri);
      await cl.connect();
      const db = client.db(dbname);
      const admin = db.admin();
      const status = await admin.replSetGetStatus();
      expect(status.members.filter((m) => m.stateStr === 'PRIMARY')).toHaveLength(1);
      expect(status.members.filter((m) => m.stateStr === 'SECONDARY')).toHaveLength(4);
  }, 60 * 1000);


References:

- https://github.com/typegoose/mongodb-memory-server/issues/911
- https://typegoose.github.io/mongodb-memory-server/docs/guides/common-issues
- https://github.com/typegoose/mongodb-memory-server/blob/master/packages/mongodb-memory-server-core/src/__tests__/replset-multi.test.ts#L21