testsuite: Skip T1288_ghci in unregisterised
testsuite: Skip T1288_ghci in unregisterised

As pointed out in #16085, these ghci tests are fragile in the unregisterised
way.

sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc