backup definitions: housekeeping to remove orphaned definitions

backup definitions: housekeeping to remove orphaned definitions

- check_mk_agent, client175 & lcr are addons that have been removed so the backup
   definitions are no longer required.
- dma is not a package but a core program and has its config backup requirements
   built into the core backup include file so the addon backup definition is not
   used or needed.
- No issues found in the build after these files were removed.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>
Reviewed-by: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>