fix(query) fix the absent_over_time function for multi-partition namespace.

[yu-shipit]

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Absent function does not work with multi-partition namespaces due to not aggregating time series from different partitions

** Absent function works with multi-partition namespaces**

BREAKING CHANGES

If this PR contains a breaking change, please describe the impact and migration
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Breaking changes may include:

• Any schema changes to any Cassandra tables
• The serialized format for Dataset and Column (see .toString methods)
• Over the wire formats for Akka messages / case classes
• Changes to the HTTP public API
• Changes to query parsing / PromQL parsing

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