pgsql: Fix regression test failure caused by commit 8d74fc96db.

Fix regression test failure caused by commit 8d74fc96db.

The tests didn't considered that an error unrelated to apply changes, e.g.
"replication origin with OID %d is already active ...", could occur on the
table sync worker before starting to copy changes.

To make the test robust we instead need to check the expected error and
the source of error which will be either tablesync or apply worker.

In passing remove the harmless option "streaming = off" from Create
Subscription command as that is anyway the default.

Per buildfarm member sidewinder.

Author: Masahiko Sawada
Reviewed-by: Hou Zhijie, Vignesh C, Amit Kapila
Discussion: https://postgr.es/m/CAD21AoDeScrsHhLyEPYqN3sydg6PxAPVBboK=30xJfUVihNZDA@mail.gmail.com
Discussion: https://postgr.es/m/E1mrtvV-0002Gz-73@gemulon.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/41e66fee051619ab84828814554f73556a958850

Modified Files
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src/test/subscription/t/026_worker_stats.pl | 59 +++++++++++++++++------------
1 file changed, 34 insertions(+), 25 deletions(-)