### 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 maximum_billing_tier: Positive integer that serves as a multiplier
        of the basic price.
        Defaults to None, in which case it uses the value set in the project.
    :param maximum_bytes_billed: Limits the bytes billed for this job.
        Queries that will have bytes billed beyond this limit will fail
        (without incurring a charge). If unspecified, this will be
        set to your project default.
    :param api_resource_configs: a dictionary that contain params
        'configuration' applied for Google BigQuery Jobs API:
        https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs
        for example, {'query': {'useQueryCache': False}}. You could use it
        if you need to provide some params that are not supported by BigQueryOperator
        like args.
    :param schema_update_options: Allows the schema of the destination
        table to be updated as a side effect of the load job.
    :param query_params: a list of dictionary containing query parameter types and
        values, passed to BigQuery. The structure of dictionary should look like
        'queryParameters' in Google BigQuery Jobs API:
        https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs.
        For example, [{ 'name': 'corpus', 'parameterType': { 'type': 'STRING' },
        'parameterValue': { 'value': 'romeoandjuliet' } }]. (templated)
    :param labels: a dictionary containing labels for the job/query,
        passed to BigQuery
    :param priority: Specifies a priority for the query.
        Possible values include INTERACTIVE and BATCH.
        The default value is INTERACTIVE.
    :param time_partitioning: configure optional time partitioning fields i.e.
        partition by field, type and expiration as per API specifications.
    :param cluster_fields: Request that the result of this query be stored sorted
        by one or more columns. BigQuery supports clustering for both partitioned and