bugfix: null exception when sql columns is empty in insert on duplicate

[renliangyu857]

…te executor

• I have registered the PR changes.

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

fixes #5005

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-commenter]

Codecov Report

Merging #5033 (e8d1d02) into develop (9e6a3b5) will increase coverage by 0.17%.
The diff coverage is 50.00%.

@@              Coverage Diff              @@
##             develop    #5033      +/-   ##
=============================================
+ Coverage      49.06%   49.24%   +0.17%     
- Complexity      4092     4111      +19     
=============================================
  Files            733      733              
  Lines          26004    26005       +1     
  Branches        3211     3212       +1     
=============================================
+ Hits           12759    12805      +46     
+ Misses         11887    11839      -48     
- Partials        1358     1361       +3     

Impacted Files	Coverage Δ
...ec/mysql/MySQLInsertOnDuplicateUpdateExecutor.java	30.97% <50.00%> (-0.17%)	⬇️
...erver/storage/file/session/FileSessionManager.java	49.04% <0.00%> (-0.64%)	⬇️
...very/registry/zk/ZookeeperRegisterServiceImpl.java	61.76% <0.00%> (+0.73%)	⬆️
...rage/redis/store/RedisTransactionStoreManager.java	67.23% <0.00%> (+3.70%)	⬆️
...java/io/seata/server/storage/SessionConverter.java	89.09% <0.00%> (+9.09%)	⬆️
...va/io/seata/server/console/vo/GlobalSessionVO.java	55.88% <0.00%> (+33.82%)	⬆️

[slievrly]

LGTM

[funky-eyes]

LGTM