Rolling back tests for WG14 DR145

Several build bots are failing with surprising behavior, so it's less
clear whether we do or don't implement this DR properly.

https://lab.llvm.org/buildbot/#/builders/91/builds/10454
https://lab.llvm.org/buildbot/#/builders/109/builds/40668
https://lab.llvm.org/buildbot/#/builders/139/builds/23334