refactor(db): 优化测试事务中的互斥锁使用

- 重构 queryWithRetry 和 execWithRetry 方法中的互斥锁逻辑，提升代码可读性
- 确保在测试事务中对 testMu 的锁定和解锁操作更加清晰，避免潜在的并发问题

db/query.go

@@ -63,15 +63,21 @@ func (that *HoTimeDB) queryWithRetry(query string, retried bool, args ...interfa
 	processedArgs := that.processArgs(args)
 
 	if that.testTx != nil {
-		if that.testMu != nil { that.testMu.Lock() }
+		if that.testMu != nil {
+			that.testMu.Lock()
+		}
 		resl, err = that.testTx.Query(query, processedArgs...)
 		that.LastErr.SetError(err)
 		if err != nil {
-			if that.testMu != nil { that.testMu.Unlock() }
+			if that.testMu != nil {
+				that.testMu.Unlock()
+			}
 			return nil
 		}
 		result := that.Row(resl)
-		if that.testMu != nil { that.testMu.Unlock() }
+		if that.testMu != nil {
+			that.testMu.Unlock()
+		}
 		return result
 	} else if that.Tx != nil {
 		resl, err = that.Tx.Query(query, processedArgs...)
@@ -129,9 +135,13 @@ func (that *HoTimeDB) execWithRetry(query string, retried bool, args ...interfac
 	processedArgs := that.processArgs(args)
 
 	if that.testTx != nil {
-		if that.testMu != nil { that.testMu.Lock() }
+		if that.testMu != nil {
+			that.testMu.Lock()
+		}
 		resl, e = that.testTx.Exec(query, processedArgs...)
-		if that.testMu != nil { that.testMu.Unlock() }
+		if that.testMu != nil {
+			that.testMu.Unlock()
+		}
 	} else if that.Tx != nil {
 		resl, e = that.Tx.Exec(query, processedArgs...)
 	} else {