Can't easily differentiate between dashboard dropdown widgets added for multiple datasets (confusing UI experience)

### Environment

SaaS (https://sentry.io/)

### Steps to Reproduce

## 1. Go to a dashboard and create a dropdown filter with `+`. Choose the `Errors` dataset, in this example, with value `sdk.name`.

-

## 2. Create another dropdown filter in the spans dataset for the same value `sdk.name`

-

## 3. There are now two dropdowns for `sdk.name`, however, it is unclear which dataset each dropdown refers to and is confusing, because it looks redundant

### Expected Result

Less confusing UI experience when selecting a filter value across multiple datasets. It should at least be clear which dataset each dropdown refers to.

### Actual Result

See above

### Product Area

Dashboards

### Link

_No response_

### DSN

_No response_

### Version

_No response_

Start at the dashboard dropdown-filter entry point and reproduce the duplicate sdk.name case with the Errors and spans datasets. Trace how the two dropdowns are presented, then verify that the dashboard UI clearly distinguishes their datasets when both filters exist.

Written by the indexing model from the issue text.