Change Webhook Creation Criteria to behave more like UI/API

[mhadertelekom]

Update Webhook Creation Criteria to Align with Artifactory UI/API Behavior

Description:

Currently the creation of release-bundle-webhook-resources has a different policy inside the terraform provider than in the API or UI. The field "registered_release_bundle_names" is mandatory inside the terraform provider. UI/API behave differently.

This pull request:

1. Refines the webhook creation logic in the Terraform provider for Artifactory to better align with the behavior of the Artifactory UI and API
2. Aligns the tests that are done in the Terraform provider according to the changes from (1)
3. Updates the documentation accordingly

These improvements ensure a more intuitive user experience for customers managing Artifactory webhooks via Terraform.

[github-actions]

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