Timestamp field gets special handling in aggregations in Scripting API

[luk-kaminski]

Description

Timestamp field gets special handling in aggregations in Scripting API.
/nocl

Motivation and Context

When timestamp field is used in aggregations, we want to aggregate in ranges.
Limit field from grouping changes its function - it defines number of equal ranges the timerange will be split into for bucketing.

How Has This Been Tested?

Manually.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have requested a documentation update.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.