[ska][x-pack] relocate platform tests [4] (#219691)

## Summary

Part of https://github.com/elastic/kibana-team/issues/1503

This PR is mostly about moving tests from `x-pack/test` to
`x-pack/platform/test`

Before:

```
x-pack/test/
     | - api_integration/apis/management/
     | - api_integration/apis/monitoring/
     | - api_integration/apis/osquery/
     | - automatic_import_api_integration
     | - monitoring_api_integration/
     | - saved_object_api_integration/
```

After: 
```
x-pack/platform/test/
     | - api_integration/apis/management/
     | - api_integration/apis/monitoring/
     | - api_integration/apis/osquery/
     | - automatic_import_api_integration
     | - monitoring_api_integration/
     | - saved_object_api_integration/
```

Additional:

- `x-pack/test/api_integration/apis/osquery/config.ts` was move to
platform stateful manifest to match `osquery` plugin (shared, platform)
- `automatic_import_api_integration` config files were moved to platform
stateful manifest to match `automatic_import` plugin (shared, platform)
- `x-pack/test/common/lib/test_data_loader.ts` is required by SO api
tests and was copied to `x-pack/platform/test/common`

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

packages/kbn-check-mappings-update-cli/current_mappings.json

@@ -4022,4 +4022,4 @@
     "dynamic": false,
     "properties": {}
   }
-}
+}