testsuite: Mark TH tests as fragile in LLVM built external-interpreter
testsuite: Mark TH tests as fragile in LLVM built external-interpreter

Due to #16087. This drops the previous explicit list of broken tests and rather
encompasses the entire set of tests since they all appear to be broken.

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