Rework workaround for GCC regarding -fno-lifetime-dse

### Describe the bug

https://github.com/llvm/llvm-project/issues/24952 is causing failures in sycl-ls,
so we have to revert https://github.com/intel/llvm/commit/6ac63129b7ef3413c9f86b81e9d33a619f94f911 and apply workarounds in https://github.com/intel/llvm/commit/e676cb09f0b23ec572fefe09aa7882876797eb79.

bader left a comment [(intel/llvm#20292)](https://github.com/intel/llvm/pull/20292#issuecomment-3377857991)
I suggest we recover https://github.com/intel/llvm/commit/6ac63129b7ef3413c9f86b81e9d33a619f94f911 and implement a workaround for sycl-ls, rather than add more changes in the community code to recover from previous community code modifications.

### To reproduce

revert e676cb09f0b23ec572fefe09aa7882876797eb79 and reland 6ac63129b7ef3413c9f86b81e9d33a619f94f911
run sycl-ls, you should see SEGV.

### Environment

- OS: [e.g Windows/Linux]
- Target device and vendor: [e.g. Intel GPU]
- DPC++ version: [e.g. commit hash or output of `clang++ --version`]
- Dependencies version: [e.g. the output of `sycl-ls --verbose`]

### Additional context

_No response_