[6.14.z] Fix assertions in file repo tests

[Satellite-QE]

Cherrypick of PR: #15138

Problem Statement

Several file-repo tests have been failing too long for a wrong assertion message.

Solution

Fix them all with this PR in a near term.

PRT test Cases example

trigger: test-robottelo
pytest: tests/foreman/cli/test_repository.py -k 'upload_remove_srpm_content or upload_file_to_file_repo or remove_file or file_repo_contains_only_newer_file'

[Satellite-QE]

trigger: test-robottelo
pytest: tests/foreman/cli/test_repository.py -k 'upload_remove_srpm_content or upload_file_to_file_repo or remove_file or file_repo_contains_only_newer_file'

[Satellite-QE]

PRT Result

Build Number: 7067
Build Status: SUCCESS
PRT Comment: pytest tests/foreman/cli/test_repository.py -k upload_remove_srpm_content or upload_file_to_file_repo or remove_file or file_repo_contains_only_newer_file --external-logging
Test Result : ========= 4 passed, 136 deselected, 172 warnings in 831.34s (0:13:51) ==========