[FLINK-36143][ES6][ES7] Intro retry-on-conflict param to resolve Sink ES occurred "version conflict"

[leosanqing]

When I used ES connector Write update datas, it occurred "version conflict", like this " org.elasticsearch.index.engine.VersionConflictEngineException: [project][1140860]: version conflict, current version [5] is different than the one provided [4] " When we set the conf failure-handler = ignore, It lead to lost data, and if set the conf failure-handler = fail, job will restore. this cost is too heavy. maybe second try it will success.

so I intro this conf param, this will make job failed cost smaller.

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[leosanqing]

@schulzp @alpinegizmo @aljoscha @rmetzger Has any body to review my code? thk ❤️❤️

[leosanqing]

Thanks for your advices，and I fixed this. Has anybody can review my code?

Thank you for your patch! I am not an official maintainer. Your changes look reasonable, however, they lack test coverage. One other thing I noticed: The newly introduced constant RETRY_ON_CONFLICT_NUM does not follow the naming convention of other config options in ElasticsearchConnectorOptions: Most of them appear to end on [...]_OPTION but do not have the type-indicating suffix. Renaming it to sink.retries-on-conflict could eliminate the confusion wether this is a boolean flag or a number.

[leosanqing]

@reswqa @mtfelisb hi guys,could you review my pr? thx

[leosanqing]

@rmetzger hi, thx for your triggering. I see there has some error when run IT case. And there also has same error in before PR . Is there some problems in project? The leatest merged pr doesn't have this step, latest un-merged PRs both have this error.