testing: fix finding tests on new cmake versions

testing: fix finding tests on new cmake versions

By chance, cmake was installed by homebrew without any restrictions,
and so version 4.0.2 happened to be installed which does no longer
use the option "--force-new-ctest-process". Changed the analysis to
look for "/bin/ctest" instead. This should work for a long time.

Task-number: PYSIDE-2221
Change-Id: Idc16063953ba82d4053cc60a7e0ef11b71b7b571
Pick-to: 6.9
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
(cherry picked from commit 03de4672557d80b34f9c9ef1e654a4117c621e65)

Gbp-Pq: Name testing-fix-finding-tests-on-new-cmake-versions.patch