### 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)

"""
    Executes BigQuery SQL queries in a specific BigQuery database.
    This operator does not assert idempotency.
    This operator is deprecated.
    Please use :class:`airflow.providers.google.cloud.operators.bigquery.BigQueryInsertJobOperator`
    :param sql: the SQL code to be executed as a single string, or
        a list of str (sql statements), or a reference to a template file.
        Template references are recognized by str ending in '.sql'
    :param destination_dataset_table: A dotted
        ``(<project>.|<project>:)<dataset>.<table>`` that, if set, will store the results
        of the query. (templated)
    :param write_disposition: Specifies the action that occurs if the destination table
        already exists. (default: 'WRITE_EMPTY')
    :param create_disposition: Specifies whether the job is allowed to create new tables.
        (default: 'CREATE_IF_NEEDED')
    :param allow_large_results: Whether to allow large results.
    :param flatten_results: If true and query uses legacy SQL dialect, flattens
        all nested and repeated fields in the query results. ``allow_large_results``
        must be ``true`` if this is set to ``false``. For standard SQL queries, this
        flag is ignored and results are never flattened.
    :param gcp_conn_id: (Optional) The connection ID used to connect to Google Cloud.
    :param udf_config: The User Defined Function configuration for the query.
        See https://cloud.google.com/bigquery/user-defined-functions for details.
    :param use_legacy_sql: Whether to use legacy SQL (true) or standard SQL (false).