azurerm_monitor_diagnostic_setting - Support dynamic block from unprovisioned data source for log/metric

[magodo]

This PR mainly remove the default value for log/metirc's enabled (which is apparently a breaking change), in order to allow dynamic block which based on some unprovisioned data source, e.g. azurerm_monitor_diagnostic_categories whose resource_id set to some to-be-provisioned resource.

Due to hashicorp/terraform#28340, currently all we can do is to not alter the block data during planning if compatibility with the dynamic feature was desired. In this case, we shall not set the default value.

Fixes #9923, #6254

[magodo]

Close due to hashicorp/terraform#28340 is fixed in TF v0.15.2.

[github-actions]

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