Caddy access logs log client errors at "level": "ERROR"

[tgeoghegan]

Successfully serving an HTTP 404 response to a request will show up in Caddy access logs with "level": "ERROR", despite the fact that the server hasn't made any error. See this discussion thread on caddy.community for more details and discussion of some options for solutions.

[mholt]

What if I submit a PR for this and we can duke it out there, @francislavoie 😄

[francislavoie]

@mholt that code is already being touched by a couple other PRs so there'll be merge conflicts. Probably best to wait for #6088 and #6082

[mholt]

It is a 1-line change AFAICT, so I just went ahead and did it real quick; just decided to go with INFO level for 4xx.