Update model description attribute map

[VipulMascarenhas]

Description

When loading DataScienceModel from yaml, the model_file_description attribute remains empty since the attribute map value is incorrect. There were no breaking changes before as this property was set when create() is called.

This PR updates the attribute mapping value from model_file_description to model_description, without updating the property name.

Example

yaml_model = DataScienceModel.from_yaml(uri="tests/unitary/with_extras/aqua/test_data/deployment/aqua_finetuned_model.yaml")

print(yaml_model.model_file_description)
{'models': [{'bucketName': 'service-managed-models',
   'namespace': 'namespace',
   'objects': [{'name': 'service_models/model-name/commit-id/artifact/README.md',
     'sizeInBytes': 3836,
     'version': '5707cfc1-499b-4ce0-aeec-32e2336c5195'},
    {'name': 'service_models/model-name/commit-id/artifact/config.json',
     'sizeInBytes': 596,
...
...

Tests

> python -m pytest -q tests/unitary/default_setup/model/test_datascience_model.py
============================================ test session starts =============================================
platform darwin -- Python 3.8.18, pytest-7.4.0, pluggy-1.0.0
rootdir: /Users/vmascarenhas/workspace/git/accelerated-data-science
configfile: pytest.ini
plugins: Faker-24.9.0, anyio-4.2.0
collected 35 items

tests/unitary/default_setup/model/test_datascience_model.py ...................................        [100%]

============================================= 35 passed in 3.79s =============================================