[clang-cl] [Sema] Do not prefer integral conversion over floating-to-integral...

[clang-cl] [Sema] Do not prefer integral conversion over floating-to-integral for MS compatibility 19.28 and higher.

As of MSVC 19.28 (2019 Update 8), integral conversion is no longer preferred over floating-to-integral, and so MSVC is more standard conformant and will generate a compiler error on ambiguous call.
Cf. https://godbolt.org/z/E8xsdqKsb.
Initially found during the review of D99641.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D99663