### 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)

"""
    Update BigQuery Table Schema
    Updates fields on a table schema based on contents of the supplied schema_fields_updates
    parameter. The supplied schema does not need to be complete, if the field
    already exists in the schema you only need to supply keys & values for the
    items you want to patch, just ensure the "name" key is set.
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:BigQueryUpdateTableSchemaOperator`
    :param schema_fields_updates: a partial schema resource. see
        https://cloud.google.com/bigquery/docs/reference/rest/v2/tables#TableSchema
    **Example**: ::
        schema_fields_updates=[
            {"name": "emp_name", "description": "Some New Description"},
            {"name": "salary", "policyTags": {'names': ['some_new_policy_tag']},},
            {"name": "departments", "fields": [
                {"name": "name", "description": "Some New Description"},
                {"name": "type", "description": "Some New Description"}
            ]},
        ]
    :param include_policy_tags: (Optional) If set to True policy tags will be included in