chore(observability): Prefer using Display for logging errors

[jszwedko]

The CONTRIBUTING guide accidentally had an example of using Debug, but
we'd decided to prefer Display for errors.

Fixes #6380

Signed-off-by: Jesse Szwedko jesse@szwedko.me

[fanatid]

👍

[pablosichert]

There's a lot more occurrences if you search for = ? and , ?. However I'm not sure if they need to be adjusted for values that are not an error?

[lukesteensen]

Makes sense! Agree with preferring Display in general, though there may be some cases where Debug works fine. We should just try to avoid any that are inconsistent with our formatting or otherwise too development-focused (as opposed to vector-user focused).

[jszwedko]

@pablosichert

There's a lot more occurrences if you search for = ? and , ?. However I'm not sure if they need to be adjusted for values that are not an error?

I'll merge this PR since this since it is an improvement, but I agree, we should think about where it makes sense to use % in more places. I also agree with Luke that debug might be fine in some circumstances so long as it outputs something useful to users.