observium-agent: Update to version 24.4

observium-agent: Update to version 24.4

- Update from version 23.1 to 24.4
- Update of rootfile not required
- Changelog is not provided in the source tarbal. Ther is a text changelog at
   https://www.observium.org/svn.log but it is not clear if this is for the community
   version used here or for the subscription based version. There is also no reference
   to any version numbers so you can't easily tell which changes are in this version and
   which not.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>