Summary:
Making code more succinct and cleaning up style.

Changing code like the following:
```for (const auto& column : record_batch) {
    ASSERT_EQ(1, column->Size());
  }
```

to

```
ASSERT_THAT(record_batch, Each(ColWrapperSizeIs(1)));
```

Test Plan: Existing tests

Reviewers: yzhao, #engineering

Reviewed By: yzhao, #engineering

Differential Revision: https://phab.corp.pixielabs.ai/D2964

GitOrigin-RevId: f66f16ad0f0cc0835f6da4ec440b0a7b6fca4769