### 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 self.hook is None:
            self.log.info("Executing: %s", self.sql)
            self.hook = BigQueryHook(
                gcp_conn_id=self.gcp_conn_id,
                use_legacy_sql=self.use_legacy_sql,
                location=self.location,
                impersonation_chain=self.impersonation_chain,
            )
        if isinstance(self.sql, str):
            job_id: str | list[str] = self.hook.run_query(
                sql=self.sql,
                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,
            )
        elif isinstance(self.sql, Iterable):
            job_id = [