refactor: deduplicate owner_ids logic

[shiftinv]

Summary

Removes some duplication related to fetching owner_id(s) in Bot._fill_owners and Bot.is_owner.
Waiting for connect isn't necessary anymore if we do the login first, which puts http into a usable state.

Checklist

• If code changes were made, then they have been tested
  • I have updated the documentation to reflect the changes
  • I have formatted the code properly by running pdm lint
  • I have type-checked the code by running pdm pyright
• This PR fixes an issue
• This PR adds something new (e.g. new method or parameters)
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)

[EQUENOS]

Lgtm