Description of problem:

Custom satellite-answer file is not included in the backup when generated using satellite-maintain command.

Version-Release number of selected component (if applicable):
Satellite 6.15.1

How reproducible:
100%

Steps to Reproduce:
1. Deploy a fresh Satellite 6.15
2. Create a custom satellite answer file under /root.
3. Update the satellite.yml with custom answer file path.

4. Execute #satellite-installer command.
5. Take a backup of the satellite server using below command:

1. satellite-maintain backup offline --skip-pulp-content \
   --assumeyes /var/backup
    
   Actual results:

 - The custom satellite answer file is not included inside config_files.tar.gz generated inside /var/backup/.

Expected results:

 - The custom satellite answer file should be included in the backup archive. The restore task or satellite-clone fails without the availability of the satellite answers file at the desired location.

Workaround:

Manually copy the file and insert into on the tarball.

1. unzip the config_files.tar.gz (do NOT untar):

~~~
cd /backup/directory
gunzip config_files.tar.gz
~~~

2. Append the answer file:

~~~
tar -rvf config_files.tar /root/custom-answers.yaml
~~~

3. Gzip it again:

~~~
gzip config_files.tar
~~~