Exclude org.eclipse.jgit from transitive inclusion

The org.eclipse.jgit jar file is already provided by the git client
plugin.  Let's not risk that a 6.9.0 copy of the library is loaded into
the same Java process that is running either JGit 6.10.0 (with git client
plugin 5.0.0) or JGit 7.0.0 with git client plugin 6.0.0)

blueocean-git-pipeline/pom.xml

@@ -39,6 +39,13 @@
       <artifactId>org.eclipse.jgit.ssh.jsch</artifactId>
       <!-- TODO this is hard to manage; if needed, should be in BOM -->
       <version>6.9.0.202403050737-r</version>
+      <exclusions>
+        <!-- Exclude the jgit library because it is provided by git client plugin -->
+        <exclusion>
+          <groupId>org.eclipse.jgit</groupId>
+          <artifactId>org.eclipse.jgit</artifactId>
+        </exclusion>
+      </exclusions>
     </dependency>
 
     <!-- test dependencies -->