replace some fmt.Sprintfs with strconv

Teeny-tiny optimizations:

    BenchmarkSprintf-10       37735996    32.31  ns/op  0 B/op  0 allocs/op
    BenchmarkItoa-10         591945836     2.031 ns/op  0 B/op  0 allocs/op
    BenchmarkFormatUint-10   593701444     2.014 ns/op  0 B/op  0 allocs/op

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/cri/server/helpers.go

@@ -112,7 +112,7 @@ func makeContainerName(c *runtime.ContainerMetadata, s *runtime.PodSandboxMetada
 		s.Name,      // 1: pod name
 		s.Namespace, // 2: pod namespace
 		s.Uid,       // 3: pod uid
-		strconv.FormatUint(uint64(s.Attempt), 10), // 4: attempt number of creating the container
+		strconv.FormatUint(uint64(c.Attempt), 10), // 4: attempt number of creating the container
 	}, nameDelimiter)
 }