Add feature to prevent creation of Ephemeral resources

[jwillemsen]

What feature do you want to see added?

A new option to prevent the creation of Ephemeral resources, at the moment the new option is set any lock of a resource which is not there would let the job wait on the resource to be created (so it makes #619 (comment) block forever)

Upstream changes

No response

Are you interested in contributing this feature?

Sorry, at this moment not enough time and only did some very minor jenkins plugin work in the past, so it will be a lot of learning