### 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: BigQueryTableAsyncHook, dataset: str, table_id: str, project_id: str
    ) -> bool:
        """
        Create client session and make call to BigQueryTableAsyncHook and check for the table in
        Google Big Query.
        :param hook: BigQueryTableAsyncHook Hook class
        :param dataset:  The name of the dataset in which to look for the table storage bucket.
        :param table_id: The name of the table to check the existence of.
        :param project_id: The Google cloud project in which to look for the table.
            The connection supplied to the hook must provide
            access to the specified project.
        """
        async with ClientSession() as session:
            try:
                client = await hook.get_table_client(
                    dataset=dataset, table_id=table_id, project_id=project_id, session=session
                )
                response = await client.get()
                return True if response else False
            except ClientResponseError as err:
                if err.status == 404:
                    return False
                raise err
class BigQueryTablePartitionExistenceTrigger(BigQueryTableExistenceTrigger):