Use "unexpected status code returned from %q: %d; expecting %d" log message format
instead of less clear format "unexpected status code returned from %q; expecting %d; got %d"
This is a follow-up for c612bb165e
ioutil.ReadAll is deprecated since Go1.16 - see https://tip.golang.org/doc/go1.16#ioutil
VictoriaMetrics requires at least Go1.18, so it is OK to switch from ioutil.ReadAll to io.ReadAll.
This is a follow-up for 02ca2342ab