[Fleet] Fix crashes when installing a package with a lot of saved obj…

…ects (#148141)

**Resolves: #147695,
#148174
**Related to: #145851,
#137420

## Summary

This PR improves the stability of the Fleet packages installation
process with many saved objects.

1. Changed mappings of the `installed_kibana` and `package_assets`
fields from `nested` to `object` with `enabled: false`. Values of those
fields were retrieved from `_source`, and no queries or aggregations
were performed against them. So the mappings were unused, while during
the installation of packages containing more than 10,000 saved objects,
an error was thrown due to the nested field limitations:

   ```
Error installing security_detection_engine 8.4.1: The number of nested
documents has exceeded the allowed limit of
   [10000].
This limit can be set by changing the
[index.mapping.nested_objects.limit] index level setting.
   ```
2. Improved the deletion of previous package assets by switching from
sending multiple `savedObjectsClient.delete` requests in parallel to a
single `savedObjectsClient.bulkDelete` request. Multiple parallel
requests were causing the Elasticsearch cluster to stop responding for
some time; see [this
ticket](#147695) for more info.

**Before**
![Screenshot 2022-12-28 at 11 09
35](https://user-images.githubusercontent.com/1938181/209816219-ade6dd0a-0d56-4acc-929e-b88571f0fe81.png)

**After**
![Screenshot 2022-12-28 at 13 56
44](https://user-images.githubusercontent.com/1938181/209816209-16c69922-4ae2-4589-9aa4-5a28050037f4.png)

src/core/server/integration_tests/saved_objects/migrations/check_registered_types.test.ts

@@ -85,7 +85,7 @@ describe('checking migration metadata changes on all registered SO types', () =>
         "endpoint:user-artifact": "f94c250a52b30d0a2d32635f8b4c5bdabd1e25c0",
         "endpoint:user-artifact-manifest": "8c14d49a385d5d1307d956aa743ec78de0b2be88",
         "enterprise_search_telemetry": "fafcc8318528d34f721c42d1270787c52565bad5",
-        "epm-packages": "2915aee4302d4b00472ed05c21f59b7d498b5206",
+        "epm-packages": "7d80ba3f1fcd80316aa0b112657272034b66d5a8",
         "epm-packages-assets": "9fd3d6726ac77369249e9a973902c2cd615fc771",
         "event_loop_delays_daily": "d2ed39cf669577d90921c176499908b4943fb7bd",
         "exception-list": "fe8cc004fd2742177cdb9300f4a67689463faf9c",

x-pack/plugins/fleet/server/saved_objects/index.ts

@@ -266,19 +266,13 @@ const getSavedObjectTypes = (
           },
         },
         installed_kibana: {
-          type: 'nested',
-          properties: {
-            id: { type: 'keyword' },
-            type: { type: 'keyword' },
-          },
+          type: 'object',
+          enabled: false,
         },
         installed_kibana_space_id: { type: 'keyword' },
         package_assets: {
-          type: 'nested',
-          properties: {
-            id: { type: 'keyword' },
-            type: { type: 'keyword' },
-          },
+          type: 'object',
+          enabled: false,
         },
         install_started_at: { type: 'date' },
         install_version: { type: 'keyword' },

x-pack/plugins/fleet/server/services/epm/archive/storage.ts

@@ -102,10 +102,9 @@ export async function removeArchiveEntries(opts: {
 }) {
   const { savedObjectsClient, refs } = opts;
   if (!refs) return;
-  const results = await Promise.all(
-    refs.map((ref) => savedObjectsClient.delete(ASSETS_SAVED_OBJECT_TYPE, ref.id))
+  return savedObjectsClient.bulkDelete(
+    refs.map((ref) => ({ id: ref.id, type: ASSETS_SAVED_OBJECT_TYPE }))
   );
-  return results;
 }
 
 export async function saveArchiveEntries(opts: {

x-pack/plugins/fleet/server/services/epm/packages/remove.ts

@@ -125,11 +125,8 @@ async function deleteKibanaAssets(
   // in the case of a partial install, it is expected that some assets will be not found
   // we filter these out before calling delete
   const assetsToDelete = foundObjects.map(({ saved_object: { id, type } }) => ({ id, type }));
-  const promises = assetsToDelete.map(async ({ id, type }) => {
-    return savedObjectsClient.delete(type, id, { namespace });
-  });
 
-  return Promise.all(promises);
+  return savedObjectsClient.bulkDelete(assetsToDelete, { namespace });
 }
 
 function deleteESAssets(