fix txn opt (#17982)

问题：一个请求中，有多个语句。当第一个语句为begin时，下一条语句会提交事务。
原因：begin语句时，设置的option，执行完后没有立即清理。导致下一条语句执行时，创建了新事务。
修改：option每次复位。

Approved by: @qingxinhome, @sukki37

pkg/frontend/back_exec.go

@@ -332,7 +332,7 @@ func doComQueryInBack(backSes *backSession, execCtx *ExecCtx,
 				return err
 			}
 		}
-
+		execCtx.txnOpt.Close()
 		execCtx.stmt = stmt
 		execCtx.isLastStmt = i >= len(cws)-1
 		execCtx.tenant = tenant

pkg/frontend/mysql_cmd_executor.go

@@ -34,10 +34,11 @@ import (
 	"github.com/confluentinc/confluent-kafka-go/v2/kafka"
 	"github.com/fagongzi/goetty/v2"
 	"github.com/google/uuid"
-	"github.com/matrixorigin/matrixone/pkg/catalog"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 
+	"github.com/matrixorigin/matrixone/pkg/catalog"
+
 	"github.com/matrixorigin/matrixone/pkg/clusterservice"
 	"github.com/matrixorigin/matrixone/pkg/common/moerr"
 	"github.com/matrixorigin/matrixone/pkg/common/runtime"
@@ -2291,6 +2292,7 @@ func executeStmtWithWorkspace(ses FeSession,
 	//1. start txn
 	//special BEGIN,COMMIT,ROLLBACK
 	beginStmt := false
+	execCtx.txnOpt.Close()
 	switch execCtx.stmt.(type) {
 	case *tree.BeginTransaction:
 		execCtx.txnOpt.byBegin = true
@@ -2806,6 +2808,7 @@ func doComQuery(ses *Session, execCtx *ExecCtx, input *UserInput) (retErr error)
 		if ses.proc != nil {
 			ses.proc.UnixTime = proc.UnixTime
 		}
+		execCtx.txnOpt.Close()
 		execCtx.stmt = stmt
 		execCtx.isLastStmt = i >= len(cws)-1
 		execCtx.tenant = tenant

pkg/frontend/txn.go

@@ -142,6 +142,13 @@ type FeTxnOption struct {
 	byRollback bool
 }
 
+func (opt *FeTxnOption) Close() {
+	opt.byBegin = false
+	opt.autoCommit = true
+	opt.byCommit = false
+	opt.byRollback = false
+}
+
 const (
 	defaultServerStatus uint32 = uint32(SERVER_STATUS_AUTOCOMMIT)
 	defaultOptionBits   uint32 = OPTION_AUTOCOMMIT