pgsql: pg_stat_statements: Remove duplicated tests for SET statements

pg_stat_statements: Remove duplicated tests for SET statements

This looks like a copy-paste mistake introduced in de2aca288569, that
has added checks for more patterns of SET statements while ignoring the
original test block that existed.

Backpatch down to where this has been introduced, as this shaves some
cycles.

Author: Sergei Kornilov
Discussion: https://postgr.es/m/5689421699428803@mail-sendbernar-production-main-46.myt.yp-c.yandex.net
Backpatch-through: 16

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/108161bcb9cc6df45ed9200ca935c63b2cad4666

Modified Files
--------------
contrib/pg_stat_statements/expected/utility.out | 27 -------------------------
contrib/pg_stat_statements/sql/utility.sql      | 13 ------------
2 files changed, 40 deletions(-)