reset spm ctx before batched multi stmt fallback to execute one by one

src/observer/mysql/obmp_query.cpp

@@ -498,6 +498,7 @@ int ObMPQuery::process_single_stmt(const ObMultiStmtItem &multi_stmt_item,
 {
   int ret = OB_SUCCESS;
   FLTSpanGuard(mpquery_single_stmt);
+  ctx_.spm_ctx_.reset();
   bool need_response_error = true;
   const bool enable_trace_log = lib::is_trace_log_enabled();
   session.get_raw_audit_record().request_memory_used_ = 0;

src/sql/ob_sql_context.h

@@ -416,6 +416,7 @@ struct ObSpmCacheCtx
   ObSpmCacheCtx()
     : bl_key_()
   {}
+  inline void reset() { bl_key_.reset(); }
   ObBaselineKey bl_key_;
 };
 

src/sql/spm/ob_spm_define.h

@@ -297,6 +297,7 @@ struct ObSpmCacheCtx : public ObILibCacheCtx
     BASELINE_PLAN,
     MAX_TYPE
   };
+  void reset();
   void set_get_normal_mode(uint64_t v) { plan_hash_value_ = v; handle_cache_mode_ = MODE_GET_NORMAL; }
   void set_get_offset_mode() { handle_cache_mode_ = MODE_GET_OFFSET; }
   void set_get_for_update_mode(uint64_t v) { plan_hash_value_ = v; handle_cache_mode_ = MODE_GET_FOR_UPDATE; }