### 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)

:param gcs_schema_object: Full path to the JSON file containing
        schema (templated). For
        example: ``gs://test-bucket/dir1/dir2/employee_schema.json``
    :param time_partitioning: configure optional time partitioning fields i.e.
        partition by field, type and  expiration as per API specifications.
        .. seealso::
            https://cloud.google.com/bigquery/docs/reference/rest/v2/tables#timePartitioning
    :param gcp_conn_id: [Optional] The connection ID used to connect to Google Cloud and
        interact with the Bigquery service.
    :param google_cloud_storage_conn_id: [Optional] The connection ID used to connect to Google Cloud.
        and interact with the Google Cloud Storage service.
    :param labels: a dictionary containing labels for the table, passed to BigQuery
        **Example (with schema JSON in GCS)**: ::
            CreateTable = BigQueryCreateEmptyTableOperator(
                task_id='BigQueryCreateEmptyTableOperator_task',
                dataset_id='ODS',
                table_id='Employees',
                project_id='internal-gcp-project',
                gcs_schema_object='gs://schema-bucket/employee_schema.json',
                gcp_conn_id='airflow-conn-id',
                google_cloud_storage_conn_id='airflow-conn-id'
            )
        **Corresponding Schema file** (``employee_schema.json``): ::
            [
              {
                "mode": "NULLABLE",
                "name": "emp_name",
                "type": "STRING"
              },
              {