pgsql: Try to stabilize reloptions test, again.

Try to stabilize reloptions test, again.

Since the test requires reproducible behavior from VACUUM, and since
DISABLE_PAGE_SKIPPING doesn't actually disable all forms of page
skipping, let's use a temporary table to avoid contention.

Back-patch to 12, like commit 3414099c.

Discussion: https://postgr.es/m/20220120052404.sonrhq3f3qgplpzj%40alap3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b700f96cffd91efbe93827d22c76b8f069809450

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