In commit b0eaa4c5, we left out a test that used a vacuum to remove dead
rows as the behavior of test was not predictable.  This test has been
rewritten to use fillfactor instead to control free space.  Since we no
longer need to remove dead rows as part of the test, put the fsm regression
test in a parallel group.

Author: John Naylor
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1L=qWp_bJ5aTc9+fy4Ewx2LPaLWY-RbR4a60g_rupCKnQ@mail.gmail.com