refactor: use slices.Contains to simplify code (#16680)

### Summary

There is a [new function](https://pkg.go.dev/slices@go1.21.0#Contains)
added in the go1.21 standard library, which can make the code more
concise and easy to read.

Signed-off-by: weifanglab <weifanglab@outlook.com>

internal/service/nlp/term_weight_test.go

@@ -18,6 +18,7 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"slices"
 	"strings"
 	"testing"
 )
@@ -713,14 +714,7 @@ func TestPretokenWithNumbers(t *testing.T) {
 	t.Run("num=false filters single digits", func(t *testing.T) {
 		result := d.Pretoken("5", false, true)
 		// Single digit should be filtered when num=false
-		found := false
-		for _, r := range result {
-			if r == "5" {
-				found = true
-				break
-			}
-		}
-		if found {
+		if slices.Contains(result, "5") {
 			t.Error("Single digit should be filtered when num=false")
 		}
 	})

internal/service/nlp/wordnet_test.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"slices"
 	"sort"
 	"testing"
 )
@@ -122,14 +123,7 @@ func TestSynsets(t *testing.T) {
 				names[i] = s.Name
 			}
 			for _, expectedName := range tt.checkNames {
-				found := false
-				for _, name := range names {
-					if name == expectedName {
-						found = true
-						break
-					}
-				}
-				if !found {
+				if !slices.Contains(names, expectedName) {
 					t.Errorf("Synsets(%q, %q) did not contain expected synset %q, got %v",
 						tt.lemma, tt.pos, expectedName, names)
 				}