itest: drop 52 JUnit 4-era dummyTest() methods

[Vest]

Every concrete *IntegrationTest class under code/src/itest/plugin/lsttokens/editcontext/** carried an empty

@Test
public void dummyTest()
{
    // Just to get Eclipse to recognize this as a JUnit 4.0 Test Case
}

Modern Eclipse + JUnit 5 recognise these classes via their inherited @Test methods on the Abstract*IntegrationTestCase parents (each parent declares 5–18 real tests). The dummies have not been needed for years; each one padded the report by one passing test that asserted nothing.

Verification

• ./gradlew compileItestJava — clean.
• ./gradlew itest --tests "plugin.lsttokens.editcontext.KitIntegrationTest" — 18 tests, 0 failures, 0 skipped (was 19 with the dummy; the 18 inherited real tests still run).
• FactIntegrationTest and FactSetIntegrationTest extend the scaffold-only AbstractIntegrationTestCase and therefore inherit no tests — they keep their 7 own real @Test methods each, verified running.
• All 52 dummies removed; grep -rln "dummyTest" code/src/itest returns nothing.

Import cleanup

Also drops the now-unused import org.junit.jupiter.api.Test; from the 40 files where dummyTest was the only local @Test usage. The 12 files with additional local @Test methods keep the import.

Stats

 52 files changed, 350 deletions(-)

Pure cleanup — no production code touched, no test coverage lost.

[Vest]

This PR exists, because I am against of useless tests :)
We use JUnit 6, so I hope everything is better.