bpo-37707: Exclude expensive unit tests from PGO task (GH-15009) (#15024)

Mark some individual tests to skip when --pgo is used.  The tests
marked increase the PGO task time significantly and likely don't
help improve optimization of the final executable.
(cherry picked from commit 52a48e62c6a94577152f9301bbe5f3bc806cfcf1)

Co-authored-by: Neil Schemenauer <nas-github@arctrix.com>
8 files changed