Remove outdated field statistics mentions from docs (#3024)

Fields statistics support for ES|QL was [removed in
8.17](elastic/kibana#197538) and the information
never made its way to the docs. This PRs fixes this by:
- removing mentions of field statistics panels in Dashboards docs
- adding a note that field statistics aren't available in ES|QL mode in
Discover. They're still there in KQL mode

As the changes get confirmed, I'll create a corresponding PR for
relevant 8.x docs

Closes: #3027

Author: florent-leborgne

explore-analyze/discover/show-field-statistics.md

@@ -15,6 +15,10 @@ Explore the fields in your data with the **Field statistics** view in **Discover
 * What does the latency look like when one of the containers is down on a Sunday?
 * Is the field type and format in the data view appropriate for the data and its cardinality?
 
+:::{note}
+Field statistics aren't available when **Discover** is in {{esql}} mode.
+:::
+
 This example explores the fields in the [sample web logs data](../index.md#gs-get-data-into-kibana), or you can use your own data.
 
 1. Go to **Discover**.
@@ -46,5 +50,5 @@ This example explores the fields in the [sample web logs data](../index.md#gs-ge
    :::
 
 7. Explore additional field types to see the statistics that **Discover** provides.
-8. To create a visualization of the field data, click ![Click the magnifying glass icon to create a visualization of the data in Lens](/explore-analyze/images/kibana-visualization-icon.png "") or ![Click the Maps icon to explore the data in a map](/explore-analyze/images/kibana-map-icon.png "") in the **Actions** column.
+8. To create a Lens visualization of the field data, click ![the magnifying glass icon to create a visualization of the data in Lens](/explore-analyze/images/kibana-visualization-icon.png "") or ![the Maps icon to explore the data in a map](/explore-analyze/images/kibana-map-icon.png "") in the **Actions** column.
 

explore-analyze/toc.yml

@@ -257,7 +257,6 @@ toc:
       - file: visualize/manage-panels.md
       - file: visualize/lens.md
       - file: visualize/esorql.md
-      - file: visualize/field-statistics.md
       - file: visualize/custom-visualizations-with-vega.md
       - file: visualize/text-panels.md
       - file: visualize/image-panels.md

explore-analyze/visualize.md

@@ -19,10 +19,9 @@ $$$panels-editors$$$
 | **Content** | **Panel type** | **Description** |
 | --- | --- | --- |
 | Visualizations | [Lens](visualize/lens.md) | Create powerful [charts](visualize/supported-chart-types.md) in {{kib}}. This is the default editor. |
-|  | [ES|QL](/explore-analyze/query-filter/languages/esql-kibana.md) | Create visualizations from ES|QL queries |
+|  | [{{esql}}](/explore-analyze/query-filter/languages/esql-kibana.md) | Create visualizations from {{esql}} queries |
 |  | [Maps](visualize/maps.md) | Create beautiful displays of your geographical data |
 |  | [Alerts](visualize/alert-panels.md) | View Observability or Security alerts in your dashboard |
-|  | [Field statistics](visualize/field-statistics.md) | Add a field statistics view of your data to your dashboards |
 |  | [Custom visualizations](visualize/custom-visualizations-with-vega.md) | Use Vega to create new types of visualizations |
 |  | | |
 | Annotations and navigation | [Collapsible sections](dashboards/arrange-panels.md#collapsible-sections) | Organize your dashboard into sections that can be collapsed and save loading time |