Revert "[CIR] Recognize constant aggregate initialization of auto vars (#166850)"
This reverts commit 5fc1b74af52093cd5229ba0e1c368d41735bb990.
This broke premerge (and premerge was failing on the patch itself):
1. https://lab.llvm.org/staging/#/builders/192/builds/10053
2. https://lab.llvm.org/staging/#/builders/21/builds/8268