Do not propagate tests if not properly implemented (yet)

src/main/scala/leon/synthesis/rules/ADTDual.scala

src/main/scala/leon/synthesis/rules/CaseSplit.scala

src/main/scala/leon/synthesis/rules/Disunification.scala

src/main/scala/leon/synthesis/rules/IfSplit.scala

src/main/scala/leon/synthesis/rules/InequalitySplit.scala