remove _last_zombie_query_time arg

[liubotao]

dag_processing class _last_zombie_query_time arg no used

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[XD-DENG]

@liubotao Thanks for the PR.

Please follow the instructions in the PR template (creating JIRA and attach the ticket number properly in commit subject as well as PR subject), before we committers can further process your PR. Thanks.

[ashb]

You have missed the crucial part of the template: Why.

What does this change achieve?

[ashb]

Please re-open this PR once you have got the information the template asks for