Begin testing on go1.23. To facilitate this, also update /x/net,
golangci-lint, staticcheck, and pebble-challtestsrv to versions which
support go1.23. As a result of these updates, also fix a handful of new
lint findings, mostly regarding passing non-static (i.e. potentially
user-controlled) format strings into Sprintf-style functions.
Additionally, delete one VA unittest that was duplicating the checks
performed by a different VA unittest, but with a context timeout bug
that caused it to break when go1.23 subtly changed DialContext behavior.
da7865cb10