[3.14] gh-145254: Fix formatting of thread safety annotations (GH-146111) (#146163)

- Add leading space so that the spacing between the previous annotation
  and the thread safety annotation looks correct.
- Remove trailing period from the link to the thread safety level.
(cherry picked from commit 580043dfae90331de15cf1504d09e2c7216182a6)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>