pw_thread_embos: Update thread iteration start
pw_thread_embos: Update thread iteration start

Updates the thread iteration to start from OS_Global.pTask, the true
full thread list starting point.

No-Docs-Update-Reason: Internal fix
Change-Id: I13c1c1b8a545b51382dbc6fbd32e725634fdeb21
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/58746
Pigweed-Auto-Submit: Armando Montanez <97ef6fdb231c129ac8827d9f0c4106bfbf57f74f@google.com>
Reviewed-by: Ewout van Bekkum <638f134dbc68778d6b859fb04a64baea2b00b021@google.com>
Commit-Queue: Auto-Submit <14637eda5603879df170705285bf30f5996692f0@pigweed.google.com.iam.gserviceaccount.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed