Python List expected, received proto.marshal.collections.repeated.Repeated for DOUBLE_ARRAY feature

For a feature of type `DOUBLE_ARRAY`, we get the values as `proto.marshal.collections.repeated.Repeated` as opposed to a Python list when read from online feature store.

#### Environment details

- OS type and version: Windows 10
- Python version: Python 3.9.0
- pip version: pip 23.1.2
- `google-cloud-aiplatform` version: 1.28.0

#### Steps to reproduce

1. Create a feature within an entity with value type as DOUBLE_ARRAY
2. Read feature values for this entity into a pandas dataframe.
3. Check the type of the value in the feature column as `proto.marshal.collections.repeated.Repeated`.

#### Code example

```python
from google.cloud.aiplatform import Featurestore

fs = Featurestore(
featurestore_name="",
project="",
location="",
)
e = fs.get_entity_type(entity_type_id="")
df = e.read(entity_ids=[""], feature_ids=[""])
print(type(df[""].iloc[0]))
```

Start by reproducing the issue through EntityType.read with a DOUBLE_ARRAY feature and inspect the resulting pandas dataframe value type. Trace the read path that converts online feature-store responses, then add coverage showing the feature column contains a Python list and run the relevant tests.

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