**Apache Airflow version**: 1.10.12

**Environment**:  Centos 7 Host

- **Cloud provider or hardware configuration**: 
- **OS** (e.g. from /etc/os-release): Ubuntu 20.04 Docker Container
- **Kernel** (e.g. `uname -a`): Linux c6c6e8230c17 3.10.0-1127.18.2.el7.x86_64 #1 SMP Sun Jul 26 15:27:06 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
- **Install tools**: Docker Compose
- **Others** ?

**What happened**:

The schema file generated by MSSQLToGCSOperator specifies that a field defined as **bit** in MSSQL, is defined as **INTEGER**.  However, the JSON file defines the value as **true**/**false**.  When attempting to import into BigQuery using the GCSOperatorToBigQuery operator, the job fails:
`Error while reading data, error message: JSON parsing error in row starting at position 0: Could not convert value 'boolean_value: false' to integer. Field: manager; Value: 0`

**What you expected to happen**:

Value should be defined as **BOOLEAN** in the schema.

**How to reproduce it**:
Ensure `dbo.Customers` table has a **bit** column:

```
export_customers = MsSqlToGoogleCloudStorageOperator(
                task_id='export_customers',
                sql='SELECT * FROM dbo.Customers;',
                bucket='mssql-export',
                filename='data/customers/export.json',
                schema_filename='schemas/export.json',
                mssql_conn_id='mssql_default',
                google_cloud_storage_conn_id='google_cloud_default',
                dag=dag
            )
```
"""Test that ndjson is split by approx_max_file_size_bytes param."""
        mssql_hook_mock = mssql_hook_mock_class.return_value
        mssql_hook_mock.get_conn().cursor().__iter__.return_value = iter(ROWS)
        mssql_hook_mock.get_conn().cursor().description = CURSOR_DESCRIPTION
        gcs_hook_mock = gcs_hook_mock_class.return_value
        expected_upload = {
            JSON_FILENAME.format(0): b"".join(NDJSON_LINES[:2]),
            JSON_FILENAME.format(1): NDJSON_LINES[2],
        }
        def _assert_upload(bucket, obj, tmp_filename, mime_type=None, gzip=False, metadata=None):
            assert BUCKET == bucket
            assert "application/json" == mime_type
            assert GZIP == gzip
            with open(tmp_filename, "rb") as file:
                assert expected_upload[obj] == file.read()
        gcs_hook_mock.upload.side_effect = _assert_upload
        op = MSSQLToGCSOperator(
            task_id=TASK_ID,
            sql=SQL,
            bucket=BUCKET,
            filename=JSON_FILENAME,
            approx_max_file_size_bytes=len(expected_upload[JSON_FILENAME.format(0)]),
        )
        op.execute(None)
    @mock.patch("airflow.providers.google.cloud.transfers.mssql_to_gcs.MsSqlHook")
    @mock.patch("airflow.providers.google.cloud.transfers.sql_to_gcs.GCSHook")
    def test_schema_file(self, gcs_hook_mock_class, mssql_hook_mock_class):