SCMSourceRetrieverTest: remove currently unused imports [JENKINS-69731]

Author: jimklimov

src/test/java/org/jenkinsci/plugins/workflow/libs/SCMSourceRetrieverTest.java

@@ -31,7 +31,6 @@
 import hudson.FilePath;
 import hudson.Functions;
 import hudson.model.Item;
-import hudson.model.Node;
 import hudson.model.Result;
 import hudson.model.TaskListener;
 import hudson.plugins.git.GitSCM;
@@ -81,7 +80,6 @@
 import static org.hamcrest.Matchers.not;
 import static org.junit.Assert.*;
 import org.junit.ClassRule;
-import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.BuildWatcher;