### 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)

BigQueryUpdateTableSchemaOperator,
    BigQueryUpsertTableOperator,
    BigQueryValueCheckOperator,
)
from airflow.providers.google.cloud.triggers.bigquery import (
    BigQueryCheckTrigger,
    BigQueryGetDataTrigger,
    BigQueryInsertJobTrigger,
    BigQueryIntervalCheckTrigger,
    BigQueryValueCheckTrigger,
)
from airflow.serialization.serialized_objects import SerializedDAG
from airflow.utils.timezone import datetime
from tests.test_utils.db import clear_db_dags, clear_db_runs, clear_db_serialized_dags, clear_db_xcom
TASK_ID = "test-bq-generic-operator"
TEST_DATASET = "test-dataset"
TEST_DATASET_LOCATION = "EU"
TEST_GCP_PROJECT_ID = "test-project"
TEST_DELETE_CONTENTS = True
TEST_TABLE_ID = "test-table-id"
TEST_GCS_BUCKET = "test-bucket"
TEST_GCS_DATA = ["dir1/*.csv"]
TEST_SOURCE_FORMAT = "CSV"
DEFAULT_DATE = datetime(2015, 1, 1)
TEST_DAG_ID = "test-bigquery-operators"
TEST_TABLE_RESOURCES = {"tableReference": {"tableId": TEST_TABLE_ID}, "expirationTime": 1234567}
VIEW_DEFINITION = {
    "query": f"SELECT * FROM `{TEST_DATASET}.{TEST_TABLE_ID}`",
    "useLegacySql": False,
}