The DT_RPATH or DT_RUNPATH value of %{_libdir} that's present in
%{_libexecdir}/installed-tests/Flatpak/testlibrary is intentional [1].
It's meant to make the installed test run against the Flatpak binaries
produced by the same build by forcing the use of the prefix specified
during the build.
[1] Upstream commit d19f6c330aa42e17
https://github.com/flatpak/flatpak/commit/d19f6c330aa42e17
Resolves: RHEL-4220
