[llvm] [memprof] Omit the key/data lengths for the frame table (PR #89711)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

I'm going to discard this PR.  We would need to route the writer trait to even more places (than present in this patch) to correctly invoke `Info.ReadKeyDataLength()` (yes, with `Info`, not as the static method).  The impact on the file size is very small for the number of places we would need to touch.

@teresajohnson Thank you for reviewing this patch!

https://github.com/llvm/llvm-project/pull/89711