pgsql: Try to stabilize the reloptions test.

Try to stabilize the reloptions test.

Where we test vacuum_truncate's effects, sometimes this is failing to
truncate as expected on the build farm.  That could be explained by page
skipping, so disable it explicitly, with the theory that commit fe246d1c
didn't go far enough.

Back-patch to 12, where the vacuum_truncate tests were added.

Discussion: https://postgr.es/m/CA%2BhUKGLT2UL5_JhmBzUgkdyKfc%3D5J-gJSQJLysMs4rqLUKLAzw%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/3414099c338bf619c00dd82d96f29a9668a3bf07

Modified Files
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src/test/regress/expected/reloptions.out | 4 ++--
src/test/regress/sql/reloptions.sql      | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)