应用运行中数据库表添加一个字段，马上对该表insert操作会导致NPE

- [ ] I have searched the [issues](https://github.com/seata/seata/issues) of this repository and believe that this is not a duplicate.

### Ⅰ. Issue Description
业务运行的时候，修改表结构，添加一列字段，seata client就会抛出NullPointerException

### Ⅱ. Describe what happened

If there is an exception, please attach the exception trace:

```
java.sql.SQLException: java.lang.NullPointerException
at io.seata.rm.datasource.exec.ExecuteTemplate.execute(ExecuteTemplate.java:112)
at io.seata.rm.datasource.exec.ExecuteTemplate.execute(ExecuteTemplate.java:49)
at io.seata.rm.datasource.PreparedStatementProxy.execute(PreparedStatementProxy.java:54)
at sun.reflect.GeneratedMethodAccessor199.invoke
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59)
at com.sun.proxy.$Proxy228.execute
at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46)
at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74)
at sun.reflect.GeneratedMethodAccessor242.invoke
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:63)
at com.sun.proxy.$Proxy226.update
at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50)
at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)
at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)
at sun.reflect.GeneratedMethodAccessor237.invoke
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:63)
at com.sun.proxy.$Proxy225.update
at sun.reflect.GeneratedMethodAccessor237.invoke
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)
at com.baomidou.mybatisplus.plugins.OptimisticLockerInterceptor.intercept(OptimisticLockerInterceptor.java:71)
at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61)
at com.sun.proxy.$Proxy225.update
at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)
at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:185)
at sun.reflect.GeneratedMethodAccessor416.invoke
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
at com.sun.proxy.$Proxy120.insert
at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:278)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:57)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
at com.sun.proxy.$Proxy209.insert
at com.baomidou.mybatisplus.service.impl.ServiceImpl.insert(ServiceImpl.java:98)
at com.baomidou.mybatisplus.service.impl.ServiceImpl$$FastClassBySpringCGLIB$$3e2398a4.invoke()
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at io.seata.spring.annotation.GlobalTransactionalInterceptor.invoke(GlobalTransactionalInterceptor.java:87)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
```

### Ⅲ. Describe what you expected to happen
查看源代码可以发现每次操作之前Executor都会校验connectionPoxy的lockKeys
如果tablemeta与当前数据库对应不上会返回一个空值导致proxy获取不到锁
发现源码中可通过修改上图中的配置自动刷新tablemeta功能
client.rm.tableMetaCheckEnable=true 默认值false
TABLE_META_CHECKER_INTERVAL = 60000ms （无法修改）

希望可以新增支持动态刷新表结构功能，或者能提供配置刷新间隔时间的参数注入

### Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. 应用启动并连接seata
2. 新增一个字段
3. 马上对该表进行insert操作

### Ⅴ. Anything else we need to know?
None

### Ⅵ. Environment:

- JDK version : 1.8
- OS : SentOS 7+
- Others: seata-all-1.2.0

Reproduce the sequence in the issue: start Seata, add a column, then immediately insert into the table. Trace the metadata and lock-key handling from io.seata.rm.datasource.exec.ExecuteTemplate.execute through PreparedStatementProxy, then inspect client.rm.tableMetaCheckEnable and TABLE_META_CHECKER_INTERVAL. Done means the insert no longer causes a NullPointerException after a schema change and the requested refresh behavior is defined and verified.

Written by the indexing model from the issue text.