[6.15.z] setup_org_for_a_rh_repo fix

[Satellite-QE]

Cherrypick of PR: #13970

Problem Statement

AttributeError: 'Manifest' object has no attribute 'path'

Solution

Follow idiom of creating a temporary file and into it, copying an in-memory object, then using it as a file.

I'm not sure how and when it got broken, I hit it when looking at the results of test_negative_without_attach_with_lce. I haven't yet tested extensively to make sure this doesn't break function _setup_org_for_a_rh_repo in other cases but it seems like it couldn't have worked.

[Satellite-QE]

trigger: test-robottelo
pytest: tests/foreman/cli/test_activationkey.py::test_positive_add_redhat_and_custom_products tests/foreman/cli/test_host.py::test_negative_without_attach_with_lce tests/foreman/cli/test_reporttemplates.py::test_positive_generate_hostpkgcompare

[Satellite-QE]

PRT Result

Build Number: 5718
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/cli/test_activationkey.py::test_positive_add_redhat_and_custom_products tests/foreman/cli/test_host.py::test_negative_without_attach_with_lce tests/foreman/cli/test_reporttemplates.py::test_positive_generate_hostpkgcompare
Test Result : ============ 2 failed, 1 passed, 59 warnings in 1054.82s (0:17:34) =============