revert forceinline for MakeString (#21943)
### Description
revert forceinline for MakeString.
This change reverts https://github.com/microsoft/onnxruntime/pull/21893.
The forceinline was introduced for performance considerations, however
it turns out to have some notable binary size increase, which is a
concern for some binary size sensitive platforms like Android.
I made a few tests locally and found it is not related to whether or not
have used the template struct `if_char_array_make_ptr_t` trick. So I
have to revert this back.
