inspect_template_name changed from required to optional

[modular-magician]

changed inspect_template_name from required to optional and added test cases.
fixes hashicorp/terraform-provider-google#11858

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Release Note Template for Downstream PRs (will be copied)

dlp: changed `inspect_template_name` field from required to optional in `google_data_loss_prevention_job_trigger` resource

Derived from GoogleCloudPlatform/magic-modules#8036