collab: Increase number of returned extensions to 1,000 (#31983)

This PR increases the number of returned extensions from the extension
API to 1,000 (up from 500).

We'll need a better solution at some point, but for now we can keep
bumping this number.

Closes https://github.com/zed-industries/zed/issues/31067.

Release Notes:

- N/A

crates/collab/src/api/extensions.rs

@@ -66,7 +66,7 @@ async fn get_extensions(
             params.filter.as_deref(),
             provides_filter.as_ref(),
             params.max_schema_version,
-            500,
+            1_000,
         )
         .await?;