regress: fix test instability

Alvaro Herrera <alvherre@alvh.no-ip.org>

Commit: 91130dd316f71ff8a5f044daf0b8303c290e57b2
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2022-08-05T09:55:52Z
Releases: 11.17
regress: fix test instability

Having additional triggers in a test table made the ORDER BY clauses in
old queries underspecified.  Add another column there for stability.

Per sporadic buildfarm pink.

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