Refactor KibanaMigrator, improve readability, maintainability and UT (e…

…lastic#155693)

Addresses the following feedback:
elastic#154151 (comment)

Similar to what has been done for ZDT, the goal of this PR is to extract
the logic of the `runV2Migration()` from the `KibanaMigrator` into a
separate file.

The PR also fixes some incomplete / incorrect UTs and adds a few missing
ones.

packages/core/elasticsearch/core-elasticsearch-server-internal/src/retry_call_cluster.ts

@@ -48,7 +48,7 @@ export const retryCallCluster = <T extends Promise<unknown>>(apiCaller: () => T)
  * Retries the provided Elasticsearch API call when an error such as
  * `AuthenticationException` `NoConnections`, `ConnectionFault`,
  * `ServiceUnavailable` or `RequestTimeout` are encountered. The API call will
- * be retried once a second, indefinitely, until a successful response or a
+ * be retried once every `delay` millis, indefinitely, until a successful response or a
  * different error is received.
  *
  * @example

packages/core/saved-objects/core-saved-objects-base-server-internal/index.ts

@@ -6,6 +6,7 @@
  * Side Public License, v 1.
  */
 
+export { DEFAULT_INDEX_TYPES_MAP } from './src/constants';
 export { LEGACY_URL_ALIAS_TYPE, type LegacyUrlAlias } from './src/legacy_alias';
 export {
   getProperty,

packages/core/saved-objects/core-saved-objects-base-server-internal/src/constants.ts

@@ -0,0 +1,116 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { IndexTypesMap } from './mappings';
+
+/**
+ * This map holds the default breakdown of SO types per index (pre 8.8.0)
+ */
+export const DEFAULT_INDEX_TYPES_MAP: IndexTypesMap = {
+  '.kibana_task_manager': ['task'],
+  '.kibana': [
+    'action',
+    'action_task_params',
+    'alert',
+    'api_key_pending_invalidation',
+    'apm-indices',
+    'apm-server-schema',
+    'apm-service-group',
+    'apm-telemetry',
+    'app_search_telemetry',
+    'application_usage_daily',
+    'application_usage_totals',
+    'book',
+    'canvas-element',
+    'canvas-workpad',
+    'canvas-workpad-template',
+    'cases',
+    'cases-comments',
+    'cases-configure',
+    'cases-connector-mappings',
+    'cases-telemetry',
+    'cases-user-actions',
+    'config',
+    'config-global',
+    'connector_token',
+    'core-usage-stats',
+    'csp-rule-template',
+    'dashboard',
+    'endpoint:user-artifact-manifest',
+    'enterprise_search_telemetry',
+    'epm-packages',
+    'epm-packages-assets',
+    'event_loop_delays_daily',
+    'exception-list',
+    'exception-list-agnostic',
+    'file',
+    'file-upload-usage-collection-telemetry',
+    'fileShare',
+    'fleet-fleet-server-host',
+    'fleet-message-signing-keys',
+    'fleet-preconfiguration-deletion-record',
+    'fleet-proxy',
+    'graph-workspace',
+    'guided-onboarding-guide-state',
+    'guided-onboarding-plugin-state',
+    'index-pattern',
+    'infrastructure-monitoring-log-view',
+    'infrastructure-ui-source',
+    'ingest-agent-policies',
+    'ingest-download-sources',
+    'ingest-outputs',
+    'ingest-package-policies',
+    'ingest_manager_settings',
+    'inventory-view',
+    'kql-telemetry',
+    'legacy-url-alias',
+    'lens',
+    'lens-ui-telemetry',
+    'map',
+    'metrics-explorer-view',
+    'ml-job',
+    'ml-module',
+    'ml-trained-model',
+    'monitoring-telemetry',
+    'osquery-manager-usage-metric',
+    'osquery-pack',
+    'osquery-pack-asset',
+    'osquery-saved-query',
+    'query',
+    'rules-settings',
+    'sample-data-telemetry',
+    'search',
+    'search-session',
+    'search-telemetry',
+    'searchableList',
+    'security-rule',
+    'security-solution-signals-migration',
+    'siem-detection-engine-rule-actions',
+    'siem-ui-timeline',
+    'siem-ui-timeline-note',
+    'siem-ui-timeline-pinned-event',
+    'slo',
+    'space',
+    'spaces-usage-stats',
+    'synthetics-monitor',
+    'synthetics-param',
+    'synthetics-privates-locations',
+    'tag',
+    'telemetry',
+    'todo',
+    'ui-metric',
+    'upgrade-assistant-ml-upgrade-operation',
+    'upgrade-assistant-reindex-operation',
+    'uptime-dynamic-settings',
+    'uptime-synthetics-api-key',
+    'url',
+    'usage-counters',
+    'visualization',
+    'workplace_search_telemetry',
+  ],
+};