### Apache Airflow version

main (development)

### What happened

1. When not providing `project_id` to `BigQueryGetDataOperator` in deferrable mode (`project_id=None`), the query generated by `generate_query` method is bugged, i.e.,: 

````sql
from `None.DATASET.TABLE_ID` limit ...
````

2. `as_dict` param does not work `BigQueryGetDataOperator`.

### What you think should happen instead

1. When `project_id` is `None` - it should be removed from the query along with the trailing dot, i.e.,:

````sql
from `DATASET.TABLE_ID` limit ...
````

2. `as_dict` should be added to the serialization method of `BigQueryGetDataTrigger`.

### How to reproduce

1. Create a DAG file with `BigQueryGetDataOperator` defined as follows:
```python
BigQueryGetDataOperator(
        task_id="bq_get_data_op",
        # project_id="PROJECT_ID",  <-- Not provided
        dataset_id="DATASET",
        table_id="TABLE",
        use_legacy_sql=False,
        deferrable=True
    )
````

2. 1. Create a DAG file with `BigQueryGetDataOperator` defined as follows:
```python
BigQueryGetDataOperator(
        task_id="bq_get_data_op",
        project_id="PROJECT_ID",
        dataset_id="DATASET",
        table_id="TABLE",
        use_legacy_sql=False,
        deferrable=True,
        as_dict=True
    )
````

### Operating System

Debian

### Versions of Apache Airflow Providers

_No response_

### Deployment

Official Apache Airflow Helm Chart

### Deployment details

_No response_

### Anything else

The `generate_query` method is not unit tested (which would have prevented it in the first place) - will be better to add one.

### 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)

mock_hook.return_value.insert_job.assert_called_once_with(
            configuration=configuration,
            location=TEST_DATASET_LOCATION,
            job_id=real_job_id,
            nowait=True,
            project_id=TEST_GCP_PROJECT_ID,
            retry=DEFAULT_RETRY,
            timeout=None,
        )
        assert result == real_job_id
    @mock.patch("airflow.providers.google.cloud.operators.bigquery.BigQueryHook")
    def test_execute_copy_success(self, mock_hook):
        job_id = "123456"
        hash_ = "hash"
        real_job_id = f"{job_id}_{hash_}"
        configuration = {
            "copy": {
                "sourceTable": "aaa",
                "destinationTable": "bbb",
            }
        }
        mock_configuration = {
            "configuration": configuration,
            "jobReference": "a",
        }
        mock_hook.return_value.insert_job.return_value = MagicMock(job_id=real_job_id, error_result=False)
        mock_hook.return_value.generate_job_id.return_value = real_job_id
        mock_hook.return_value.insert_job.return_value.to_api_repr.return_value = mock_configuration
        op = BigQueryInsertJobOperator(
            task_id="copy_query_job",