Extend ISS mixed content export case with flatpak and import

[vsedmik]

Problem Statement

Satellite 6.17 introduces support for Flatpak content.
In #17013 (this PR is based on that) we add basic support and cases for flatpaks.

As per the issue linked bellow we also need to ensure that ISS export and import work for flatpaks the same as for standard container-type repositories.

Solution

We already have a test case for mixed content-types export (including container) so I've decided to extend it with a flatpak repo and the import portion (which we needed anyway).

Flatpak repo creation somewhat differs from other repos (it can be created only by mirroring of a remote-repo after a flatpak-remote scans the remote index), but that's handled by the function_synced_flatpak_repo fixture. O

Some additional minor fixes:

• removed the extra product for the container-repo (all repos share just one product)
• removed some obvious comments

In this PR please focus just on the ISS part in tests/foreman/cli/test_satellitesync.py
(the rest is reviewed in #17013)

Related Issues

https://issues.redhat.com/browse/SAT-29562

PRT test Cases example

trigger: test-robottelo
pytest: tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos
Katello:
  katello: 11223
  hammer-cli-katello: 971

[vsedmik]

trigger: test-robottelo
pytest: tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos
Katello:
  katello: 11223
  hammer-cli-katello: 971

[Satellite-QE]

PRT Result

Build Number: 9552
Build Status: SUCCESS
PRT Comment: pytest tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos --external-logging
Test Result : ========== 1 passed, 36 deselected, 45 warnings in 1565.71s (0:26:05) ==========

[vsedmik]

rebased

[vsedmik]

trigger: test-robottelo
pytest: tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos

[vsedmik]

looks like pip install -qU -r requirements.txt failed in PRT

[vsedmik]

trigger: test-robottelo
pytest: tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos

[Satellite-QE]

PRT Result

Build Number: 9619
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos --external-logging
Test Result : =========== 36 deselected, 45 warnings, 1 error in 836.24s (0:13:56) ===========

[vsedmik]

trigger: test-robottelo
pytest: tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos
Katello:
  katello: 11223
  hammer-cli-katello: 971

[Satellite-QE]

PRT Result

Build Number: 9620
Build Status: SUCCESS
PRT Comment: pytest tests/foreman/cli/test_satellitesync.py -k test_postive_export_import_cv_with_mixed_content_repos --external-logging
Test Result : ========== 1 passed, 36 deselected, 45 warnings in 1619.50s (0:26:59) ==========