Revert "[Clang][CWG1815] Support lifetime extension of temporary created by...

Revert "[Clang][CWG1815] Support lifetime extension of temporary created by aggregate initialization using a default member initializer (#87933)"

This reverts commit 17daa204.

Multiple examples on the PR
https://github.com/llvm/llvm-project/pull/87933

show regressions, so reverting until they can be fixed in the followup.