perf: avoid unnecessary byteslice->string before fmt %s verb (#10364)

fmt.Printf or fmt.Sprintf already know how to convert a
byteslice into a string when building the output; we shouldn't
incur the unnecessary string(byteslice) conversion.
Using Bencher, we can see improvements such as
https://dashboard.github.orijtech.com/benchmark/3245b8e4bbbd44a597480319aaa4b9fe
which in independent experiments show:

* time/op (ns/op)
FormatIt-8	1.2µs ± 2%	1.1µs ± 10%	-11.77%	(p=0.000 n=10+9)

* speed (MB/s)
FormatIt-8	0.71GB/s ± 2%	0.80GB/s ± 9%	+13.59%	(p=0.000 n=10+9)

* allocs/op (B/op)
FormatIt-8	2.0kB ± 0%	1.1kB ± 0%	-45.62%	(p=0.000 n=10+10)

* allocs/op (count/op)
FormatIt-8	11 ± 0%	        9.0 ± 0%	-18.18%	(p=0.000 n=10+10)

Fixes #10363

x/genutil/client/cli/init.go

@@ -61,7 +61,7 @@ func displayInfo(info printInfo) error {
 		return err
 	}
 
-	_, err = fmt.Fprintf(os.Stderr, "%s\n", string(sdk.MustSortJSON(out)))
+	_, err = fmt.Fprintf(os.Stderr, "%s\n", sdk.MustSortJSON(out))
 
 	return err
 }