[Cribl]: Datastream field is unreadable after namespace-rerouting column was added

## Summary

On the Cribl integration configuration page, the **Datastream** field is hard to read. This is the most important field in the datastream-mapping section (it determines where Cribl `_dataId` values get routed), but after the recent update that introduced the namespace-rerouting column, there is no longer enough horizontal room for it to display legibly.

## Details

The mapping section renders three columns per row:

- **Cribl `_dataId` field** (free-text input)
- **Datastream** (dropdown — "MAPS TO")
- **Namespace** (free-text, default)

The Datastream dropdown is now too narrow to show full datastream names. Selected values and dropdown options are truncated (e.g. `logs-a…`, `logs-entityanal…`, `logs-google_w…`, `metrics-endpo…`, `metrics-apach…`, `logs-azure.sig…`), so users cannot tell which datastream a mapping actually targets — both for already-configured mappings and when selecting a new one.

This regressed after the namespace-rerouting column was added, which consumed horizontal space previously available to the Datastream field. The configuration page also **cannot be resized** to reclaim room, so there is no workaround.

## Impact

- Users can't reliably read or verify their `_dataId` → datastream mappings.
- Truncated dropdown options make it easy to select the wrong datastream (e.g. two `metrics-endpo…` entries are indistinguishable).

## Expected

The Datastream field should be readable — wide enough to show full (or clearly distinguishable) datastream names, with full values visible on selection and in the dropdown list. Consider giving the Datastream column priority in the layout, allowing the page/section to be resized, or showing full names via tooltip/wrapping.

## Notes

- Component: Cribl integration configuration UI
- Regression introduced by: the [recent change ](https://github.com/elastic/integrations/pull/17792)adding the namespace-rerouting column
- A screenshot demonstrating the truncation was shared with this report (dropdown showing truncated `logs-*` / `metrics-*` options and a selected `logs-a…` value).