[v10.0.x] Previews: remove docs (#68406)

Previews: remove docs (#68042)

remove dashboard preview docs

(cherry picked from commit 8dee5d3364)

Co-authored-by: Artur Wierzbicki <artur.wierzbicki@grafana.com>

docs/sources/setup-grafana/image-rendering/_index.md

@@ -130,29 +130,6 @@ RENDERING_CLUSTERING_TIMEOUT=30
 }
 ```
 
-##### Cluster mode `contextPerRenderKey` (experimental)
-
-> **Note:** This feature is available in Image Renderer v3.4.0 and later versions.
-
-In `contextPerRenderKey` mode, the plugin will reuse the same [browser context](https://chromedevtools.github.io/devtools-protocol/tot/Target/#method-createBrowserContext) for all rendering requests sharing the same `renderKey` auth cookie and target domain within a short time window. Each new request will open a new page within the existing context. Contexts are closed automatically after 5s of inactivity.
-
-In the case of `contextPerRenderKey` mode, the `clustering.max_concurrency` option refers to the number of open contexts rather than the number of open pages. There is no way to limit the number of open pages in a context.
-
-`contextPerRenderKey` was designed to improve the performance of the [dashboard previews crawler]({{< relref "../../search/dashboard-previews/#about-the-dashboard-previews-crawler" >}}).
-
-```json
-{
-  "rendering": {
-    "mode": "clustered",
-    "clustering": {
-      "mode": "contextPerRenderKey",
-      "maxConcurrency": 5,
-      "timeout": 30
-    }
-  }
-}
-```
-
 #### Reusable (experimental)
 
 When using the rendering mode `reusable`, one browser instance will be created and reused. A new incognito page will be opened for each request. This mode is experimental since, if the browser instance crashes, it will not automatically be restarted. You can achieve a similar behavior using `clustered` mode with a high `maxConcurrency` setting.