Fix expected files for backup

[vsedmik]

Fix for #241

These files are expected inside the backup folder:

ONLINE:
With pulp: ['candlepin.dump', 'config_files.tar.gz', '.config.snar', 'foreman.dump', 'metadata.yml', 'pg_globals.dump', 'pulpcore.dump', 'pulp_data.tar', '.pulp.snar']
Skip pulp: ['candlepin.dump', 'config_files.tar.gz', '.config.snar', 'foreman.dump', 'metadata.yml', 'pg_globals.dump', 'pulpcore.dump']

OFFLINE:
With pulp: ['config_files.tar.gz', '.config.snar', 'metadata.yml', 'pgsql_data.tar.gz', '.postgres.snar', 'pulp_data.tar', '.pulp.snar']
Skip pulp: ['config_files.tar.gz', '.config.snar', 'metadata.yml', 'pgsql_data.tar.gz', '.postgres.snar']

Test results against Satellite 6.10.0 snap 20:

(venv) [vsedmik@localhost testfm]$ pytest -s --ansible-host-pattern server --ansible-user=root --ansible-inventory testfm/inventory tests/test_backup.py::test_positive_backup_online tests/test_backup.py::test_positive_backup_online_skip_pulp_content tests/test_backup.py::test_positive_backup_offline tests/test_backup.py::test_positive_backup_offline_skip_pulp_content
=========================================================================================================== test session starts ===========================================================================================================
platform linux -- Python 3.9.7, pytest-3.6.1, py-1.10.0, pluggy-0.6.0
ansible: 2.9.20
rootdir: /home/vsedmik/PycharmProjects/testfm, inifile:
plugins: ansible-2.2.3
collected 4 items                                                                                                                                                                                                                         
...
======================================================================================================= 4 passed in 670.91 seconds ========================================================================================================

[vsedmik]

As per previous discussion, the offline backup at 6.10 contains the same files for Satellite and Capsule, so I have unified it under the OFFLINE_BACKUP_FILES.

Test results:

Satellite:
(venv) [vsedmik@localhost testfm]$ pytest -s --ansible-host-pattern server --ansible-user=root --ansible-inventory testfm/inventory tests/test_backup.py
=========================================================================================================== test session starts ===========================================================================================================
platform linux -- Python 3.9.7, pytest-3.6.1, py-1.10.0, pluggy-0.6.0
ansible: 2.9.20
rootdir: /home/vsedmik/PycharmProjects/testfm, inifile:
plugins: ansible-2.2.3
collected 18 items
...
====================================================================================================== 18 passed in 3084.54 seconds =======================================================================================================

Capsule:
(venv) [vsedmik@localhost testfm]$ pytest -s --ansible-host-pattern server --ansible-user=root --ansible-inventory testfm/inventory tests/test_backup.py
=========================================================================================================== test session starts ===========================================================================================================
platform linux -- Python 3.9.7, pytest-3.6.1, py-1.10.0, pluggy-0.6.0
ansible: 2.9.20
rootdir: /home/vsedmik/PycharmProjects/testfm, inifile:
plugins: ansible-2.2.3
collected 18 items                                                                                                                                                                                                                        
...
====================================================================================================== 18 passed in 1171.09 seconds =======================================================================================================

[Gauravtalreja1]

@vsedmik ACK
Thanks for the PR, merging this after 2 approvals :)