test-catalog does not work as installed test as it hard-codes CATALOG_DIR

[mbiebl]

test-catalog uses

         '', '', '-DCATALOG_DIR="@0@"'.format(build_catalog_dir)],

This absolute path is embedded into the binary. As a result, it does not really work as an installed test and the binary simply abort with an assertion when run from /usr/lib/systemd/tests/
Another side effect is, that it trips up our reproducibility checks in Debian. See
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=908365#25

Given that, should we stop installing test-catalog or is there a way to avoid encoding an absolute path in the binary and make it also work when installed?

[yuwata]

Please test #10046.