[InstCombine] Fix flag propagation in `foldSelectIntoOp` (#162003)

Consider the following transform:
```
C = binop float A, nnan OOp
D = select ninf, i1 cond, float C, float A
->
E = select ninf, i1 cond, float OOp, float Identity
F = binop float A, E
```
We cannot propagate ninf from the original select, because OOp may be
inf, and the flag only guarantees that FalseVal (op OOp) is never
infinity.
Examples: -inf + +inf = NaN, -inf - -inf = NaN, 0 * inf = NaN
Specifically, if the original select has both ninf and nnan, we can
safely propagate the flag.

Alive2: 
+ fadd: https://alive2.llvm.org/ce/z/TWfktv
+ fsub: https://alive2.llvm.org/ce/z/RAsjJb
+ fmul: https://alive2.llvm.org/ce/z/8eg4ND

Closes https://github.com/llvm/llvm-project/issues/161634.

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