fix: fix pprof by using DefaultServeMux

replace http.NewServeMux with http.DefaultServeMux

see https://pkg.go.dev/net/http/pprof
> By default, all the profiles listed in runtime/pprof.Profile are
available (via Handler), in addition to the Cmdline, Profile, Symbol,
and Trace profiles defined in this package. If you are not using
DefaultServeMux, you will have to register handlers with the mux you are
using.

Signed-off-by: j4ckstraw <[email protected]>

Author: j4ckstraw

pkg/exporters/k8sexporter/k8s_exporter.go

@@ -81,7 +81,7 @@ func (ke *k8sExporter) startHTTPReporting(npdo *options.NodeProblemDetectorOptio
 	if npdo.ServerPort <= 0 {
 		return
 	}
-	mux := http.NewServeMux()
+	mux := http.DefaultServeMux
 
 	// Add healthz http request handler. Always return ok now, add more health check
 	// logic in the future.