Add handwritten sweeper for google_data_loss_prevention_discovery_config

[modular-magician]

Addresses #19089.

This PR:

• Adds a new sweeper to remove DiscoveryConfigs in the location passed by the sweeper (us-central1)
• Creates a sweeper that does not check for unsweepable resources, as there should be only one DiscoveryConfig of each storage type per location per project, so we must delete all DiscoveryConfigs in this location and project to avoid impacting CI tests

Release Note Template for Downstream PRs (will be copied)

Derived from GoogleCloudPlatform/magic-modules#11429

[github-actions]

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