fix: do not return a StripPrefix handler when building checker (#3559)

* fix: do not return a StripPrefix handler when building checker

already doing the strip prefix https://github.com/tyler-lloyd/azure-container-networking/blob/40b6c443d62321ee61c134bf6573ed2de9813d50/cns/healthserver/server.go#L15

so doing it inside check builder is redunant and causes the /healthz endpoint to return a 404

* chore: tabs

Author: tyler-lloyd

Diff for: cns/healthserver/healthz.go

@@ -55,7 +55,7 @@ func NewHealthzHandlerWithChecks(cnsConfig *configuration.CNSConfig) (http.Handl
 
 	// strip prefix so that it runs through all checks registered on the handler.
 	// otherwise it will look for a check named "healthz" and return a 404 if not there.
-	return http.StripPrefix("/healthz", &healthz.Handler{
+	return &healthz.Handler{
 		Checks: checks,
-	}), nil
+	}, nil
 }

Diff for: cns/healthserver/healthz_test.go

@@ -198,6 +198,7 @@ func TestNewHealthzHandlerWithChecks(t *testing.T) {
 
 			responseRecorder := httptest.NewRecorder()
 			healthHandler, err := NewHealthzHandlerWithChecks(tt.cnsConfig)
+			healthHandler = http.StripPrefix("/healthz", healthHandler)
 			require.NoError(t, err)
 
 			healthHandler.ServeHTTP(responseRecorder, httptest.NewRequest("GET", "/healthz", http.NoBody))