katello proxies also need repository configuration before installation

[evgeni]

• [x] I am familiar with the contributing guidelines.

Please cherry-pick my commits into:

• [x] Foreman 3.10/Katello 4.12
• [x] Foreman 3.9/Katello 4.11 (planned Satellite 6.15; orcharhino 6.8)
• [x] Foreman 3.8/Katello 4.10
• [x] Foreman 3.7/Katello 4.9 (Satellite 6.14)
• [x] Foreman 3.6/Katello 4.8
• [x] 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.

[github-actions[bot]]

The PR preview for 2f430ef376ffb0405db4075bea5323441ee9fe05 is available at theforeman-foreman-documentation-preview-pr-2971.surge.sh

The following output files are affected by this PR:

• Installing_Proxy/index-katello.html

show diff

show diff as HTML

[evgeni]

Mhh, no, that's also not correct. Grml.