### 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)

self.hook.run_query(
                    sql=s,
                    destination_dataset_table=self.destination_dataset_table,
                    write_disposition=self.write_disposition,
                    allow_large_results=self.allow_large_results,
                    flatten_results=self.flatten_results,
                    udf_config=self.udf_config,
                    maximum_billing_tier=self.maximum_billing_tier,
                    maximum_bytes_billed=self.maximum_bytes_billed,
                    create_disposition=self.create_disposition,
                    query_params=self.query_params,
                    labels=self.labels,
                    schema_update_options=self.schema_update_options,
                    priority=self.priority,
                    time_partitioning=self.time_partitioning,
                    api_resource_configs=self.api_resource_configs,
                    cluster_fields=self.cluster_fields,
                    encryption_configuration=self.encryption_configuration,
                )
                for s in self.sql
            ]
        else:
            raise AirflowException(f"argument 'sql' of type {type(str)} is neither a string nor an iterable")
        context["task_instance"].xcom_push(key="job_id", value=job_id)
    def on_kill(self) -> None:
        super().on_kill()
        if self.hook is not None:
            self.log.info("Cancelling running query")
            self.hook.cancel_job(self.hook.running_job_id)
class BigQueryCreateEmptyTableOperator(GoogleCloudBaseOperator):