[c10d][flight recorder] store a copy of string in entry (#119837)
Summary:
Previously, we just store the char pointer in entry, the string is a
temp object and will be destructed when we want to dump/access it.
A quick fix is to store a copy of the string, but without changing the
upstream char*.
An alternative is to change every profilingTitle into std:string, this
however would needs comprehensive overhall of the code up to the
c10d::work layer above workNCCL and RecordFunction etc.
We chose the first option for this change
Resolve #119808
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119837
Approved by: https://github.com/zdevito, https://github.com/wconstab
