[OpenMP] libomp: fix ittnotify stack stitching for teams construct

Stitching id could be overridden causing reference of destroyed object
when number of teams is 1. The patch separates stitching id store
location for teams and parallel nested in teams.

Differential Revision: https://reviews.llvm.org/D96562

GitOrigin-RevId: 493210117785c348dcbbf7fc3615020ee81d2c9d
1 file changed