Remove all modularity support

[cgwalters]

Derived from https://github.com/coreos/rpm-ostree/pull/4937

Part of https://fedoraproject.org/wiki/Changes/RetireModularity

It's dead, so let's remove all the code. I think this may cause things to silently do nothing if folks have modules layered, but at least server side builds will just stop working.

[openshift-ci[bot]]

Skipping CI for Draft Pull Request. If you want CI signal for your change, please convert it to an actual PR. You can still manually trigger a test run with /test all

[jlebon]

This is continued in https://github.com/coreos/rpm-ostree/pull/4937 again.

[cgwalters]

They're different, the change in https://github.com/coreos/rpm-ostree/pull/4937/commits/1ba3a7b0670af55f21ff285ae44248b6f73e36c2 just deletes the entrypoints to minimize code churn. This PR deletes it all.

[HuijingHei]

From failed logs, might need to remove related in src/libpriv/rpmostree-util.cxx

May 22 02:58:25.162432 kola-runext.service[2197]: + rpm-ostree override remove chrony
...
May 22 02:58:50.402554 kola-runext.service[2243]: Writing OSTree commit...done
May 22 02:58:54.682538 rpm-ostreed.service[1645]: **
May 22 02:58:54.682538 rpm-ostreed.service[1645]: rpm-ostreed:ERROR:src/libpriv/rpmostree-util.cxx:510:gboolean rpmostree_deployment_get_layered_info(OstreeRepo*, OstreeDeployment*, gboolean*, guint*, char**, char***, char***, GVariant**, GVariant**, GVariant**, GError**): assertion failed: (g_variant_dict_lookup (dict, "rpmostree.modules", "^as", &layered_modules))
May 22 02:58:54.684000 audit[1645]: ANOM_ABEND auid=4294967295 uid=0 gid=0 ses=4294967295 subj=system_u:system_r:install_t:s0 pid=1645 comm="tokio-runtime-w" exe="/usr/bin/rpm-ostree" sig=6 res=1
May 22 02:58:54.684891 rpm-ostreed.service[1645]: Bail out! rpm-ostreed:ERROR:src/libpriv/rpmostree-util.cxx:510:gboolean rpmostree_deployment_get_layered_info(OstreeRepo*, OstreeDeployment*, gboolean*, guint*, char**, char***, char***, GVariant**, GVariant**, GVariant**, GError**): assertion failed: (g_variant_dict_lookup (dict, "rpmostree.modules", "^as", &layered_modules))

[cgwalters]

OK, if CI passes on this one I think we can call it good to go.