<!--

Welcome to Apache Airflow!  For a smooth issue process, try to answer the following questions.
Don't worry if they're not all applicable; just try to include what you can :-)

If you need to include code snippets or logs, please put them in fenced code
blocks.  If they're super-long, please use the details tag like
<details><summary>super-long log</summary> lots of stuff </details>

Please delete these comment blocks before submitting the issue.

-->

**Description**

From Cloud Bigtable [documentation](https://cloud.google.com/bigtable/docs/replication-overview#how-it-works)
> Cloud Bigtable supports up to 4 replicated clusters located in Google Cloud zones where Cloud Bigtable is available.
Currently Bigtable hook and operator only support creating one replicated cluster. It would be better to add support for creating multiple replicated clusters

**Use case / motivation**

<!-- What do you want to happen?

Rather than telling us how you might implement this solution, try to take a
step back and describe what you are trying to achieve.

-->
Supporting multiple replicated clusters will be handy. It will be helpful to increase the availability and durability of the data by copying it across multiple regions or multiple zones within the same region.


tests/providers/google/cloud/hooks/test_bigtable.py
instance_method = get_client.return_value.instance
        instance_exists_method = instance_method.return_value.exists
        instance_exists_method.return_value = False
        delete_method = instance_method.return_value.delete
        self.bigtable_hook_default_project_id.delete_instance(
            instance_id=CBT_INSTANCE,
            project_id=GCP_PROJECT_ID_HOOK_UNIT_TEST,
        )
        instance_method.assert_called_once_with('instance')
        instance_exists_method.assert_called_once_with()
        delete_method.assert_not_called()
        get_client.assert_called_once_with(project_id='example-project')
    @mock.patch(
        'airflow.providers.google.common.hooks.base_google.GoogleBaseHook.project_id',
        new_callable=PropertyMock,
        return_value=GCP_PROJECT_ID_HOOK_UNIT_TEST
    )
    @mock.patch('google.cloud.bigtable.instance.Instance.create')
    @mock.patch('airflow.providers.google.cloud.hooks.bigtable.BigtableHook._get_client')
    def test_create_instance(self, get_client, instance_create, mock_project_id):