[6.14.z] Fix cli yum repo authentication test

[Satellite-QE]

Cherrypick of PR: https://github.com/SatelliteQE/robottelo/pull/16640

Problem Statement

'generator' object has no attribute 'copy'

Solution

There were multiple levels to this error:

• fix parametrization error AttributeError: 'generator' object has no attribute 'copy'
• fix assertion
• filter invalid parametrizations by adding 'yum_compatible' flag
  • 'latin-1' codec can't encode characters
  • Validation failed: Upstream password requires upstream username be set.
  • Validation failed: Upstream username is too long (maximum is 255 characters)

What was sadly not done:

• make parametrization ids readable for meanigful debugging

Related Issues

PRT test tests/foreman/cli/test_repository.py::TestRepository::test_negative_synchronize_auth_yum_repo