Improve test in 009_matviews.pl.

 Improve test in 009_matviews.pl.
 
 Ensure that the target table on the subscriber exists before executing any
 DML intended for replication.
 
 Currently, if the table is missing, the replication logic keeps retrying
 until the table is eventually created by the test. Although this behaviour
 does not cause test failures, since the table is created after the INSERT
 is published and replication eventually succeeds, however, it introduces
 unnecessary looping and delays.
 
 Author: Grem Snoort <grem.snoort@gmail.com>
 Discussion: https://postgr.es/m/CANV9Qw5HD7=Fp4nox2O7DoVctHoabRRVW9Soo4A=QipqW5B=Tg@mail.gmail.com