[ES 9.0] Remove body workaround (@elastic/kibana-management) (#217220)

## Summary

Follow up to https://github.com/elastic/kibana/pull/213375: The latest
version of the ES client fixed the issue
https://github.com/elastic/elasticsearch-js/issues/2584.

We should be able to remove all usages of `// @ts-expect-error
elasticsearch@9.0.0
https://github.com/elastic/elasticsearch-js/issues/2584`.

x-pack/platform/plugins/shared/index_management/server/routes/api/data_streams/register_post_route.ts

@@ -59,8 +59,7 @@ export function registerPostOneApplyLatestMappings({
           }
           await client.asCurrentUser.indices.putMapping({
             index: name,
-            // @ts-expect-error elasticsearch@9.0.0 https://github.com/elastic/elasticsearch-js/issues/2584
-            body: mappings,
+            ...mappings,
             write_index_only: true,
           });