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

crypto/keyring/signing_algorithms_test.go

@@ -56,7 +56,7 @@ func TestAltSigningAlgoList_Contains(t *testing.T) {
 
 func TestAltSigningAlgoList_String(t *testing.T) {
 	list := SigningAlgoList{hd.Secp256k1, notSupportedAlgo{}}
-	require.Equal(t, fmt.Sprintf("%s,notSupported", string(hd.Secp256k1Type)), list.String())
+	require.Equal(t, fmt.Sprintf("%s,notSupported", hd.Secp256k1Type), list.String())
 }
 
 type notSupportedAlgo struct {