[8.17] [Search] Add ML as required plugin to Search Assistant (#204009)…

… (#204036)

# Backport

This will backport the following commits from `main` to `8.17`:
- [[Search] Add ML as required plugin to Search Assistant
(#204009)](#204009)

<!--- Backport version: 9.4.3 -->

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

<!--BACKPORT [{"author":{"name":"Sander
Philipse","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-12-12T14:20:09Z","message":"[Search]
Add ML as required plugin to Search Assistant (#204009)\n\n##
Summary\r\n\r\nThis adds the `ml` plugin as required to the Search
Assistant so that we\r\ndon't need users to navigate to an ml-based
plugin to initiate the\r\nknowledge
base.","sha":"16d45f503a886b13b9fbc04a8cd20bb7e0f14ece","branchLabelMapping":{"^v9.0.0$":"main","^v8.18.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:fix","v9.0.0","Team:Search","backport:prev-major"],"title":"[Search]
Add ML as required plugin to Search
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Add ML as required plugin to Search Assistant (#204009)\n\n##
Summary\r\n\r\nThis adds the `ml` plugin as required to the Search
Assistant so that we\r\ndon't need users to navigate to an ml-based
plugin to initiate the\r\nknowledge
base.","sha":"16d45f503a886b13b9fbc04a8cd20bb7e0f14ece"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.0.0","branchLabelMappingKey":"^v9.0.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/204009","number":204009,"mergeCommit":{"message":"[Search]
Add ML as required plugin to Search Assistant (#204009)\n\n##
Summary\r\n\r\nThis adds the `ml` plugin as required to the Search
Assistant so that we\r\ndon't need users to navigate to an ml-based
plugin to initiate the\r\nknowledge
base.","sha":"16d45f503a886b13b9fbc04a8cd20bb7e0f14ece"}}]}] BACKPORT-->

Co-authored-by: Sander Philipse <[email protected]>

x-pack/plugins/search_assistant/kibana.jsonc

@@ -16,6 +16,7 @@
     "requiredPlugins": [
       "actions",
       "licensing",
+      "ml", // necessary for assistant's use of knowledge base in assistant package
       "observabilityAIAssistant",
       "triggersActionsUi",
       "share"

x-pack/plugins/serverless_search/kibana.jsonc

@@ -37,6 +37,8 @@
       "searchInferenceEndpoints",
       "usageCollection"
     ],
-    "requiredBundles": ["kibanaReact"]
+    "requiredBundles": [
+      "kibanaReact"
+    ]
   }
 }