In b0eaa4c5, we allow FSM to be created only after 4 pages.  One of the
tests check the FSM contents and to do that it populates many tuples in
the relation.  The FSM contents depend on the availability of freespace in
the page and it could vary because of the alignment of tuples.

This commit removes the dependency on FSM contents.

Author: Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1KADF6K1bagr0--mGv3dMcZ%3DH_Z-Qtvdfbp5PjaC6PJJA%40mail.gmail.com