### 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)

for that particular row.
    **Example Result**: ``[['Tony', 10], ['Mike', 20]``
    2. True - A Python list of dictionaries, where each dictionary represents a row. In each dictionary,
    the keys are the column names and the values are the corresponding values for those columns.
    **Example Result**: ``[{'name': 'Tony', 'age': 10}, {'name': 'Mike', 'age': 20}]``
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:BigQueryGetDataOperator`
    .. note::
        If you pass fields to ``selected_fields`` which are in different order than the
        order of columns already in
        BQ table, the data will still be in the order of BQ table.
        For example if the BQ table has 3 columns as
        ``[A,B,C]`` and you pass 'B,A' in the ``selected_fields``
        the data would still be of the form ``'A,B'``.
    **Example**: ::
        get_data = BigQueryGetDataOperator(
            task_id='get_data_from_bq',
            dataset_id='test_dataset',
            table_id='Transaction_partitions',
            project_id='internal-gcp-project',
            max_results=100,
            selected_fields='DATE',
            gcp_conn_id='airflow-conn-id'
        )
    :param dataset_id: The dataset ID of the requested table. (templated)
    :param table_id: The table ID of the requested table. (templated)
    :param project_id: (Optional) The name of the project where the data
        will be returned from. (templated)
    :param max_results: The maximum number of records (rows) to be fetched