Match Dashboard widget units with Discover units (ms vs s)

### Problem Statement

When passing custom measurements with a defined unit, such as `second` based on these docs ([Sending Performance Metrics](https://docs.sentry.io/platforms/python/tracing/span-metrics/performance-metrics/)), they show up properly on the Discover page's Bar Graph. But on the bar graph in Dashboards, they always seem to display in milliseconds even thought the table below it displays the units.

**Screenshot of graph in Discover (I'm sending 2 measurements of `second` and 1 measurement of `millisecond`)-**

**My Dashboard Widget -**

[Link to my Discover](https://francisorg.sentry.io/discover/results/?id=32327&project=-1&statsPeriod=1h)

[Link to my Dashboard](https://francisorg.sentry.io/dashboard/125311/widget/2/?statsPeriod=7d)

### Solution Brainstorm

We should make them match when the unit is provided.

### Product Area

Dashboards

Use the linked Discover and Dashboard views to reproduce the same custom measurements with second and millisecond units, then compare the bar-graph formatting with the table. The work is done when the Dashboard graph matches Discover's unit handling while the table continues to display correct units.

Written by the indexing model from the issue text.