pacific: test/lazy-omap-stats: Various enhancements

pacific: test/lazy-omap-stats: Various enhancements

Primarily removal of boost::process call to blocking deep scrub cli
command.

Fixes: https://tracker.ceph.com/issues/49727
Signed-off-by: Brad Hubbard <bhubbard@redhat.com>
(cherry picked from commit c3e28a84b04711ea8ccde16d454e5cf963a4f01a)

 Conflicts:
	src/test/lazy-omap-stats/CMakeLists.txt
          - Lacking boost library on link lbrary line
	src/test/lazy-omap-stats/lazy_omap_stats_test.cc
          - Missing an unnecessary commit to use bp::child instead of
            bp:system