[clang] Consider emitting llvm.lifetime.start/llvm.lifetime.end for variables with bypassed initialization

#181937 will add infrastructure for emitting code on entry into the scope of a variable, even if the initializer is bypassed. We could use this infrastructure to emit llvm.lifetime.start() for such variables, and drop the check at https://github.com/llvm/llvm-project/blob/3873d151c9248fed3da049d793208296413bbcc8/clang/lib/CodeGen/CGDecl.cpp#L1617 .