azurerm_iothub - update computed props in file_upload to default

[myc2h6o]

Updating acc test to check default value as well
Document already has the default values available:

terraform-provider-azurerm/website/docs/r/iothub.html.markdown

Lines 297 to 303 in f5f5f2e

	* `sas_ttl` - (Optional) The period of time for which the SAS URI generated by IoT Hub for file upload is valid, specified as an [ISO 8601 timespan duration](https://en.wikipedia.org/wiki/ISO_8601#Durations). This value must be between 1 minute and 24 hours. Defaults to `PT1H`.
	* `notifications` - (Optional) Used to specify whether file notifications are sent to IoT Hub on upload. Defaults to `false`.
	* `lock_duration` - (Optional) The lock duration for the file upload notifications queue, specified as an [ISO 8601 timespan duration](https://en.wikipedia.org/wiki/ISO_8601#Durations). This value must be between 5 and 300 seconds. Defaults to `PT1M`.
	* `default_ttl` - (Optional) The period of time for which a file upload notification message is available to consume before it expires, specified as an [ISO 8601 timespan duration](https://en.wikipedia.org/wiki/ISO_8601#Durations). This value must be between 1 minute and 48 hours. Defaults to `PT1H`.

Azure document for reference: https://learn.microsoft.com/azure/iot-hub/iot-hub-devguide-file-upload#file-upload-settings

[mbfrahry]

LGTM

[github-actions]

This functionality has been released in v3.47.0 of the Terraform Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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