Rely on self-upgrade

[ehelms]

• I am familiar with the contributing guidelines.

Please cherry-pick my commits into:

• Foreman 3.10/Katello 4.12
• Foreman 3.9/Katello 4.11 (Satellite 6.15; orcharhino 6.8)
• Foreman 3.8/Katello 4.10
• Foreman 3.7/Katello 4.9 (Satellite 6.14)
• Foreman 3.6/Katello 4.8
• Foreman 3.5/Katello 4.7 (Satellite 6.13; orcharhino 6.6/6.7)
• Foreman 3.4/Katello 4.6 (EL8 only)
• Foreman 3.3/Katello 4.5 on EL7 & EL8 (Satellite 6.12 on EL8 only; orcharhino 6.4/6.5 on EL8 only)
• We do not accept PRs for Foreman older than 3.3.

[ehelms]

This consolidates the upgrade process down into three straight forward steps:

1. Have foreman-maintain self-upgrade itself to the next version
2. Run upgrade checks
3. Run the actual upgrade

All the details of repository enablement, and module enablement are then handled by foreman-maintain itself.

@evgeni I believe this reflects what we discussed around letting self-upgrade do the work. I'm still open to the idea of a self-rollback.

[github-actions]

The PR preview for 27609de is available at theforeman-foreman-documentation-preview-pr-2995.surge.sh

The following output files are affected by this PR:

• Upgrading_Project/index-satellite.html
• Upgrading_Project_Disconnected/index-satellite.html

show diff

show diff as HTML

[asteflova]

Discussed at upstream docs meeting, will merge later today. The changes requested by ekohl have been applied.