Fix vanilla nether/end tests to correctly exercise early-return path in onPlayerLeaveIsland

[Copilot]

testOnPlayerLeaveIslandVanillaNether and testOnPlayerLeaveIslandVanillaEnd claimed to verify that movement in vanilla (non-island) worlds is ignored, but both asserted assertTrue(event.isCancelled()) — the opposite behavior. Since addon.inGameWorld was never overridden from the default true, the guard at line 292 never triggered and the tests were silently exercising the teleport-back path instead.

Changes

• Both vanilla world tests: replace stale iwm.isIslandNether/End + island.onIsland stubs with when(addon.inGameWorld(any())).thenReturn(false) and assert verify(addon, never()).getIslands() — consistent with the existing testOnPlayerLeaveIslandReturnTeleportOutsideCheckNotInGameWorld
• PlayerListener: fix grammar in debug log ("did not found" → "did not find")

// Before — wrong: doesn't override inGameWorld, asserts teleport DID happen
when(iwm.isIslandNether(any())).thenReturn(false);
when(iwm.isIslandEnd(any())).thenReturn(false);
when(island.onIsland(any())).thenReturn(false);
...
assertTrue(event.isCancelled());  // contradicts the javadoc

// After — correct: vanilla world is not a game world, early return fires
when(addon.inGameWorld(any())).thenReturn(false);
...
verify(addon, never()).getIslands();

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