Add ELS option for convert2rhel for EL7

[Gauravtalreja1]

Problem Statement

Conversion to EL7 fails since it require ELS support with --els in convert2rhel utility

Solution

Add ELS option while conversion for EL7 as per changes introduced in theforeman/foreman_ansible#746

Related Issues

https://issues.redhat.com/browse/SAT-26076

[Gauravtalreja1]

trigger: test-robottelo
pytest: tests/foreman/api/test_convert2rhel.py
theforeman:
    foreman_ansible: 746

[Satellite-QE]

PRT Result

Build Number: 9581
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/api/test_convert2rhel.py --external-logging
Test Result : ============ 2 failed, 559 warnings, 2 errors in 5412.68s (1:30:12) ============

[Gauravtalreja1]

trigger: test-robottelo
pytest: tests/foreman/api/test_convert2rhel.py
theforeman:
    foreman_ansible: 746
    foreman_remote_execution: 933

[Satellite-QE]

PRT Result

Build Number: 9641
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/api/test_convert2rhel.py --external-logging
Test Result : ================= 17 warnings, 4 errors in 4911.09s (1:21:51) ==================

[Satellite-QE]

PRT Result

Build Number: 9664
Build Status: UNSTABLE
PRT Comment: pytest tests/foreman/api/test_convert2rhel.py --external-logging
Test Result : =========== 2 failed, 841 warnings, 2 errors in 10458.45s (2:54:18) ============