[8.x] Remove useless loop

[mgrinspan]

I was going to point out that $search was incorrectly used instead of $s in the original code, but then I realized that the code still works as-is, albeit with redundant calls to str_(i)replace. Realizing this, we can just remove the loop altogether. There's also no need to call Arr::wrap for the same reason- str_(i)replace supports both arrays and strings as input.

[rcerljenko]

There's also no need for $subject variable. Just directly return the result of a ternary operation.