sync annotated Refspecs

[SHoen]

I added the jenkins-openshift.io/refspec annotation to sync additional Refspecs from a BuildConfig annotation to the Jenkins job configuration.

Testing done

I tested the change with following annotation of the BuildConfig: jenkins.openshift.io/refspec: '+refs/pull-requests//from:refs/remotes/origin/pr/'
The following screenshot shows the annotated value in the Jenkins configuration.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[SHoen]

@prdhamdh @k37y I provided a very small enhancement. Please let me know if you miss something to review/approve.