### 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)

if table_prop in job_configuration[job_type]:
                            table = job_configuration[job_type][table_prop]
                            persist_kwargs = {
                                "context": context,
                                "task_instance": self,
                                "project_id": self.project_id,
                                "table_id": table,
                            }
                            if not isinstance(table, str):
                                persist_kwargs["table_id"] = table["tableId"]
                                persist_kwargs["dataset_id"] = table["datasetId"]
                            BigQueryTableLink.persist(**persist_kwargs)
        self.job_id = job.job_id
        context["ti"].xcom_push(key="job_id", value=self.job_id)
        
        if not self.deferrable:
            job.result(timeout=self.result_timeout, retry=self.result_retry)
            self._handle_job_error(job)
            return self.job_id
        self.defer(
            timeout=self.execution_timeout,
            trigger=BigQueryInsertJobTrigger(
                conn_id=self.gcp_conn_id,
                job_id=self.job_id,
                project_id=self.project_id,
                poll_interval=self.poll_interval,
            ),
            method_name="execute_complete",
        )
    def execute_complete(self, context: Context, event: dict[str, Any]):