[chore] [exporter/splunkhec] Use NewDefaultClientConfig instead of ma…

…nually creating struct

**Description:**
This PR makes usage of `NewDefaultClientConfig` instead of manually creating the confighttp.ClientConfig struct.

**Link to tracking Issue:** open-telemetry#35457

exporter/splunkhecexporter/config_test.go

@@ -4,6 +4,7 @@
 package splunkhecexporter
 
 import (
+	"net/http"
 	"path/filepath"
 	"testing"
 	"time"
@@ -13,6 +14,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/confighttp"
+	"go.opentelemetry.io/collector/config/configopaque"
 	"go.opentelemetry.io/collector/config/configretry"
 	"go.opentelemetry.io/collector/config/configtls"
 	"go.opentelemetry.io/collector/confmap/confmaptest"
@@ -24,6 +26,8 @@ import (
 )
 
 func TestLoadConfig(t *testing.T) {
+	defaultMaxConnsPerHost := http.DefaultTransport.(*http.Transport).MaxConnsPerHost
+
 	t.Parallel()
 
 	cm, err := confmaptest.LoadConf(filepath.Join("testdata", "config.yaml"))
@@ -77,6 +81,8 @@ func TestLoadConfig(t *testing.T) {
 					IdleConnTimeout:      &idleConnTimeout,
 					HTTP2ReadIdleTimeout: 10 * time.Second,
 					HTTP2PingTimeout:     10 * time.Second,
+					Headers:              map[string]configopaque.String{},
+					MaxConnsPerHost:      &defaultMaxConnsPerHost,
 				},
 				BackOffConfig: configretry.BackOffConfig{
 					Enabled:             true,

exporter/splunkhecexporter/factory.go

@@ -64,17 +64,19 @@ func createDefaultConfig() component.Config {
 
 	defaultMaxConns := defaultMaxIdleCons
 	defaultIdleConnTimeout := defaultIdleConnTimeout
+
+	clientConfig := confighttp.NewDefaultClientConfig()
+	clientConfig.Timeout = defaultHTTPTimeout
+	clientConfig.IdleConnTimeout = &defaultIdleConnTimeout
+	clientConfig.MaxIdleConnsPerHost = &defaultMaxConns
+	clientConfig.MaxIdleConns = &defaultMaxConns
+	clientConfig.HTTP2ReadIdleTimeout = defaultHTTP2ReadIdleTimeout
+	clientConfig.HTTP2PingTimeout = defaultHTTP2PingTimeout
+
 	return &Config{
-		LogDataEnabled:       true,
-		ProfilingDataEnabled: true,
-		ClientConfig: confighttp.ClientConfig{
-			Timeout:              defaultHTTPTimeout,
-			IdleConnTimeout:      &defaultIdleConnTimeout,
-			MaxIdleConnsPerHost:  &defaultMaxConns,
-			MaxIdleConns:         &defaultMaxConns,
-			HTTP2ReadIdleTimeout: defaultHTTP2ReadIdleTimeout,
-			HTTP2PingTimeout:     defaultHTTP2PingTimeout,
-		},
+		LogDataEnabled:          true,
+		ProfilingDataEnabled:    true,
+		ClientConfig:            clientConfig,
 		SplunkAppName:           defaultSplunkAppName,
 		BackOffConfig:           configretry.NewDefaultBackOffConfig(),
 		QueueSettings:           exporterhelper.NewDefaultQueueConfig(),