Googletest export

Split the scoped trace examples into two snippets.

This doesn't have an effect in the github markdown renderer, but in some other renderers/templates, this leads them to be independently copy-pastable. In particular, the markdown rendering that Google uses internally has a copy button for each code snippet, which, before this change, would copy both lines. Bad copy button, no cookie! After this change, there will be two such buttons, one per line, and clicking a copy button will copy only the one snippet it is next to, and not the other. This is desirable because nobody will ever want to copy both lines, only one or the other.

PiperOrigin-RevId: 276079009