Revert "ptest: Enable rpath to load libraries from relative paths"

This reverts commit ecd6b8a0e3.
Using rpaths introduced a lof of buildpaths QA errors for ptest
packages. Revert the commit until better solution for the few test
cases can be found that need the rpath.

Task-number: QTBUG-105913
Change-Id: I5479629818e10c5f00841c371548bb697899e8dc
Reviewed-by: Ari Parkkila <ari.parkkila@qt.io>

recipes-qt/qt6/qt6-ptest.inc

@@ -31,6 +31,7 @@ EOF
         -DQT_BUILD_EXAMPLES=OFF \
         -DQT_ADDITIONAL_PACKAGES_PREFIX_PATH=${D}${QT6_INSTALL_LIBDIR}/cmake \
         -DCMAKE_STAGING_PREFIX=${D}${prefix} \
+        -DCMAKE_SKIP_RPATH=ON \
         -DQT_DISABLE_NO_DEFAULT_PATH_IN_QT_PACKAGES=ON \
         -DQT_FORCE_BUILTIN_TESTDATA=ON \
         ${S} \