Revert "[clang] Enable sized deallocation by default in C++14 onwards"

This reverts commit 2916b125.

Reverting due to failures on:
https://lab.llvm.org/buildbot/#/builders/216/builds/26407
https://lab.llvm.org/staging/#/builders/247/builds/5659
http://45.33.8.238/win/83485/step_7.txt