### Apache Airflow Provider(s)

google

### Versions of Apache Airflow Providers

apache-airflow 2.5.0
apache-airflow-providers-apache-beam 4.1.0
apache-airflow-providers-cncf-kubernetes 5.0.0
apache-airflow-providers-google 8.6.0
apache-airflow-providers-grpc 3.1.0

### Apache Airflow version

2.5.0

### Operating System

Debian 11

### Deployment

Official Apache Airflow Helm Chart

### Deployment details

KubernetesExecutor

### What happened

GCSToBigQueryOperator allows multiple ways to specify schema of the BigQuery table:

1. Setting autodetect == True
1. Setting schema_fields directly with autodetect == False
1. Setting a schema_object and optionally a schema_object_bucket with autodetect == False

This third method seems to be broken in the latest provider version (8.6.0) and will always result in this error:

```
[2022-12-16, 21:06:18 UTC] {taskinstance.py:1772} ERROR - Task failed with exception
Traceback (most recent call last):
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/providers/google/cloud/transfers/gcs_to_bigquery.py", line 395, in execute
    self.configuration = self._check_schema_fields(self.configuration)
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/providers/google/cloud/transfers/gcs_to_bigquery.py", line 524, in _check_schema_fields
    raise RuntimeError(
RuntimeError: Table schema was not found. Set autodetect=True to automatically set schema fields from source objects or pass schema_fields explicitly
```

The reason for this is because [this block](https://github.com/apache/airflow/blob/25bdbc8e6768712bad6043618242eec9c6632618/airflow/providers/google/cloud/transfers/gcs_to_bigquery.py#L318-L320) where `if self.schema_object and self.source_format != "DATASTORE_BACKUP":`. fails to set self.schema_fields. It only sets the local variable, schema_fields. When self._check_schema_fields is subsequently called [here](https://github.com/apache/airflow/blob/25bdbc8e6768712bad6043618242eec9c6632618/airflow/providers/google/cloud/transfers/gcs_to_bigquery.py#L395), we enter the [first block](https://github.com/apache/airflow/blob/25bdbc8e6768712bad6043618242eec9c6632618/airflow/providers/google/cloud/transfers/gcs_to_bigquery.py#L523-L528) because autodetect is false and schema_fields is not set.

### What you think should happen instead

No error should be raised if autodetect is set to False and a valid schema_object is provided

### How to reproduce

1. Create a simple BigQuery table with a single column col1:

```sql
CREATE TABLE `my-project.my_dataset.test_gcs_to_bigquery` (col1 INT);
```

2. Upload a json blob for this object to a bucket (e.g., data/schemas/table.json)
3. Upload a simple CSV for the source file to load to a bucket (e.g., data/source/file.csv)
4. Run the following command:

```py
    gcs_to_biquery = GCSToBigQueryOperator(
        task_id="gcs_to_bigquery",
        destination_project_dataset_table="my-project.my_dataset.test_gcs_to_bigquery",
        bucket="my_bucket_name",
        create_disposition="CREATE_IF_NEEDED",
        write_disposition="WRITE_TRUNCATE",
        source_objects=["data/source/file.csv"],
        source_format="CSV",
        autodetect=False,
        schema_object="data/schemas/table.json",
    )
```

### Anything else

_No response_

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

}
        )
        bq_hook.return_value.insert_job.assert_called_once_with(
            configuration={
                "query": {
                    "query": f"SELECT MAX({MAX_ID_KEY}) AS max_value FROM {TEST_EXPLICIT_DEST}",
                    "useLegacySql": False,
                    "schemaUpdateOptions": [],
                }
            },
            project_id=bq_hook.return_value.project_id,
        )
    @mock.patch("airflow.providers.google.cloud.transfers.gcs_to_bigquery.GCSHook")
    @mock.patch("airflow.providers.google.cloud.transfers.gcs_to_bigquery.BigQueryHook")
    def test_schema_fields_scanner_without_external_table_should_execute_successfully(
        self, bq_hook, gcs_hook
    ):
        """
        Check detection of schema fields if schema_fields parameter is not
        specified and fields are read from source objects correctly by the operator
        if all fields are characters. In this case operator searches for fields in source object
        and update configuration with constructed schema_fields.
        """
        bq_hook.return_value.insert_job.side_effect = [
            MagicMock(job_id=pytest.real_job_id, error_result=False),
            pytest.real_job_id,
        ]
        bq_hook.return_value.generate_job_id.return_value = pytest.real_job_id
        bq_hook.return_value.split_tablename.return_value = (PROJECT_ID, DATASET, TABLE)
        bq_hook.return_value.get_job.return_value.result.return_value = ("1",)