[chore] refactor(sumologicexporter): use confighttp.NewDefaultClientConfig (open-telemetry#31510)

Use `confighttp.NewDefaultClientConfig` instead of
`confighttp.ClientConfig{...}`.

**Link to tracking Issue:** open-telemetry#6641

**Testing:**

Unit tests

Author: andrzej-stencel

exporter/sumologicexporter/config.go

@@ -62,9 +62,9 @@ type Config struct {
 
 // createDefaultClientConfig returns default http client settings
 func createDefaultClientConfig() confighttp.ClientConfig {
-	return confighttp.ClientConfig{
-		Timeout: defaultTimeout,
-	}
+	config := confighttp.NewDefaultClientConfig()
+	config.Timeout = defaultTimeout
+	return config
 }
 
 // LogFormatType represents log_format

exporter/sumologicexporter/factory_test.go

@@ -40,7 +40,9 @@ func TestCreateDefaultConfig(t *testing.T) {
 		GraphiteTemplate:   "%{_metric_}",
 
 		ClientConfig: confighttp.ClientConfig{
-			Timeout: 5 * time.Second,
+			IdleConnTimeout: confighttp.NewDefaultClientConfig().IdleConnTimeout,
+			MaxIdleConns:    confighttp.NewDefaultClientConfig().MaxIdleConns,
+			Timeout:         5 * time.Second,
 		},
 		BackOffConfig: configretry.NewDefaultBackOffConfig(),
 		QueueSettings: qs,