Revert "[libc++][tests] Fix a few remaining instances of outdated static...

Revert "[libc++][tests] Fix a few remaining instances of outdated static assertion regexes in our test suite"

Fails like https://lab.llvm.org/buildbot/#/builders/238/builds/6278/steps/11/logs/stdio on many bots.

This reverts commit 166b3a86.