pgsql: Attempt to stabilize new window agg regression test

Attempt to stabilize new window agg regression test

This test was recently added in 3900a02c9.  It appears to be unstable in
regards to the join order presumably due to the relations at either side
of the join being equal in side.  Here we add a qual to make one of them
smaller so the planner is more likely to choose to hash the smaller of the
two.

Reported-by: Nathan Bossart, Tom Lane
Discussion: https://www.postgr.es/m/20230803235403.GC1238296@nathanxps13

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7516056c584e3f7e04269f2e80835d1433e869c4

Modified Files
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src/test/regress/expected/window.out | 10 ++++++----
src/test/regress/sql/window.sql      |  1 +
2 files changed, 7 insertions(+), 4 deletions(-)