Extend dora_metrics data source to query time series

What does this MR do and why?

This MR extends the DORA metrics data source to support time series visualization by:

1. Adding daily interval bucketing support
2. Moving DORA metrics query logic into a unified data source
3. Improving date range handling using start dates
4. Adding visualization overrides to support time series charts

These changes enable more granular analysis of DORA metrics data over time rather than single aggregated values.

Key Changes

Change	Description
New Bucketing	Added DAILY interval constant
Date Ranges	Consolidated date range handling with START_DATES mapping
Data Source	Unified DORA metrics into single data source with time series support
Visualization	Added chart customization for different metric types

References

• Related to #515445 (closed)

How to set up and validate locally

1. Start the development server
2. Navigate to a group/project analytics dashboard
3. View DORA metrics visualizations
4. Verify metrics display in both single value and time series formats
5. Test different date range selections work correctly