[8.6] [Enterprise Search] Fix pagination issue on indices page (#149833) (#149862)

# Backport

This will backport the following commits from `main` to `8.6`:
- [[Enterprise Search] Fix pagination issue on indices page
(#149833)](https://github.com/elastic/kibana/pull/149833)

<!--- Backport version: 8.9.7 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Sander
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Search] Fix pagination issue on indices page (#149833)\n\n##
Summary\r\n\r\nFixes a bug where the fetch indices request was
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BACKPORT-->

Co-authored-by: Sander Philipse <94373878+sphilipse@users.noreply.github.com>

x-pack/plugins/enterprise_search/server/routes/enterprise_search/indices.ts

@@ -120,7 +120,7 @@ export function registerIndexRoutes({
           meta: {
             page: {
               current: page,
-              size: indices.length,
+              size,
               total_pages: totalPages,
               total_results: totalResults,
             },