d/control: fix lua dependencies for librgw2

d/control: fix lua dependencies for librgw2

One can attach lua scripts as sort of hooks to implement dynamic
checks or transformations of RGW requests since Ceph Pacific. Thus, a
lua library is now required for base support and optionally one can
use the luarocks deployment and management system for Lua modules to
use more advanced scripts/modules.

With commit 46500cace6c ("rgw/test/lua: add lua integration tests
suite") the dependency relations got cleaned up, as the respective
entries were missing completely from debian/control.

But that commit is pulling in much more than required due to adding
the devel package `liblua5.3-dev` instead of the library-only
`liblua5.3-0` one, and having `luarocks` as hard dependency compared
to an optional Suggests. Fixing that avoids pulling in a whole
build/compiler/autotools/... stack with 65 new packages just when one
wants to use librgw2 or python3-rgw for simple RGW requests, or just
needs the ceph-common package, which pulls in librgw2 transitively.

This was reported by prolific community member Neobin on the Proxmox
forum [0], and then discussed on the original PR, adding the
dependencies [1].

[0]: https://forum.proxmox.com/threads/156433/post-715148
[1]: https://github.com/ceph/ceph/pull/52931#issuecomment-2441253989

Fixes: https://tracker.ceph.com/issues/68873
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>