When testing this plugin against EE 10, I found the same test-only (not production) issues in GitHubServerConfigIntegrationTest as I did when testing this plugin against EE 9. Rather than continue to adapt this test for every EE version, this PR removes any references to Jetty or Jakarta EE from the test, making the test less fragile. In their place, we substitute references to standard Java Platform functionality.

Testing done

mvn clean verify with Java 21

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