Make Jenkins login credentials optional
Description
When Jenkins is configured to not ask for credentials the username and password fields on the GitLab Jenkins service screen are not required. In the case of the linked ticket the customer is using an internal proxy. When configuring they have to use bogus credentials for the Jenkins service to save the integration.
Proposal
Make Jenkins credentials optional.
Links / references
ZD: https://gitlab.zendesk.com/agent/tickets/39263
What do you think @ayufan