[Cost] Always call substitute to record trace element
[Cost] Always call substitute to record trace element

Summary:
:
Since traces are attached to symbols, currently it will make no difference.
Calling `subst` on `Top` or on constant is constant-time.

But I need this to record `Call` trace elements for `Top`.

Reviewed By: ezgicicek

Differential Revision: D14249265

fbshipit-source-id: d3aa4ac9e

jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer