remove extra level of key indentation

[sjpb]

Took a little while to work out how best to handle epel and openhpc, but I think this is pretty clean. NB: I haven't updated the dnf_repos/README.md.

Have checked:

• Can create Pulp server (on RL8)
• Can sync repos (actually, fails with 500 errors on
  • item=epel-9-20250817T000753
  • item=OpenHPC-9-20241218T154614
  • item=OpenHPC-updates-9-20250510T003301
    but I think this is unrelated to my changes, the others sync ok
• Can run set_repos from dnf_repos. Obviously site.yml fails when it actually needs repos due to syn failure, but the resulting repo files look ok
• Can run the update-timestamps adhoc

[wtripp180901]

not seeing the 500 errors on my end, I think I might have hit them before and I'm pretty sure they were just timeouts from not having enough vCPUs