Fix update bigquery transfer config

[modular-magician]

Dynamically add update mask for changed properties instead of having a static list of all updatable properties.

In the case of service_account_name, it is only added to the update mask if it was set to a non-null value, as service_account_name cannot be removed from a transfer config using the patch API.

Fixes #16033 and #16126

Release Note Template for Downstream PRs (will be copied)

bigquerydatatransfer: fixed an error when updating `google_bigquery_data_transfer_config` related to incorrect update masks

Derived from GoogleCloudPlatform/magic-modules#9212

[github-actions]

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