Avoid 400 when importing gitlab_project_job_token_scopes with enabled not set

Summary

This change improves how the system handles a GitLab setting that forces job token scope enforcement to always be enabled.

Previously, if a user didn't explicitly set the enabled field in their configuration, the system would simply ignore it — even when the GitLab instance required it to be true. Now, when that instance-level setting is active and the user hasn't specified a value, the system automatically sets enabled to true on their behalf, avoiding unnecessary errors or confusion.

Additionally, a small fix was made to how a project ID is referenced in the test code (a minor syntax cleanup), and two new test steps were added to verify that the resource can be created without explicitly setting enabled, and that it can be successfully imported afterward.

Fixes #6777 (closed)