Feat: Make Update FAQ segment logic more concise

Because

I was looking at this recently, and I wasn't entirely happy with how I wrote this

changes the delimiter switch to a sensible default of prepend unless said otherwise
changes the adding code to a ternary instead of an if, and in doing so removes the weird double negation I had going on
updates tests to account for this

[x] I have thoroughly read and understand The Odin Project Contributing Guide
[x] The title of this PR follows the location of change: brief description of change format, e.g. Callbacks command: Update verbiage
[x] The Because section summarizes the reason for this PR
[x] The This PR section has a bullet point list describing the changes in this PR
[x] If this PR addresses an open issue, it is linked in the Issue section
[x] If applicable, I have ensured all tests related to any command files included in this PR pass, and/or all snapshots are up to date