[clang] [CIR][NFC] Update the constructor sites of `CIRGenFPOptionsRAII` (PR #182187)

[Ayokunle Amodu via cfe-commits]

ayokunle321 wrote:

@andykaylor I realized that this may be a bit of a pain to review. In cases like this, I was wondering if it was better to just set the MissingFeatures method to true and leave it at that or one and done refactors, like this, were fine. 

https://github.com/llvm/llvm-project/pull/182187