Change to workspace behaviour.

Current design:

The Lightweight checkout for Pipeline (using the 'Pipeline script from SCM' option) uses a Temporary workspace.  The Temporary workspace syncs the Jenkinsfile Script into the @Script directory, but then continues to use it for the Implicit checkout step (assuming you declarative).

JENKINS-45999

Proposed design:

Auto delete the temporary workspace for the Jenkinsfile Script checkout.  Create a workspace based on the name format field in the configuration for the implisit checkout step.

Russell Gallop