Update after plugin folder layout changes in Kibana

This require to use <kibana_root>/data for registered translations
and i18n plugin moved to core_plugins from plugins.

Refer to PR for more details:
https://github.com/elastic/kibana/pull/7562

src/core_plugins/i18n/server/__tests__/i18n.js

@@ -7,7 +7,7 @@ import process from 'child_process';
 import Promise from 'bluebird';
 
 const PATH_SEPARATOR = path.sep;
-const DATA_PATH = __dirname + PATH_SEPARATOR + 'fixtures';
+const DATA_PATH = __dirname + PATH_SEPARATOR + 'data';
 const TRANSLATION_BACKUP_PATH = DATA_PATH + '/translations_backup';
 
 const translationStorePath = i18n.getTranslationStoragePath();

src/core_plugins/i18n/server/i18n/i18n.js

@@ -12,9 +12,8 @@ const mkdirpAsync = Promise.promisify(mkdirp);
 
 const PATH_SEPARATOR = path.sep;
 const TRANSLATION_FILE_EXTENSION = 'json';
-const TRANSLATION_STORE_PATH = kibanaPackage.__dirname + PATH_SEPARATOR + 'fixtures' + PATH_SEPARATOR + 'translations';
+const TRANSLATION_STORE_PATH = kibanaPackage.__dirname + PATH_SEPARATOR + 'data' + PATH_SEPARATOR + 'translations';
 
-//TODO(hickeyma): Update to use https://github.com/elastic/kibana/pull/7562
 const getTranslationStoragePath = function () {
   return TRANSLATION_STORE_PATH;
 };

src/core_plugins/kibana/index.js

@@ -2,7 +2,7 @@ import Promise from 'bluebird';
 import { mkdirp as mkdirpNode } from 'mkdirp';
 import manageUuid from './server/lib/manage_uuid';
 import fs from 'fs';
-import i18nPlugin from '../../plugins/i18n/server/i18n/index';
+import i18nPlugin from '../i18n/server/i18n/index';
 import ingest from './server/routes/api/ingest';
 import kibanaPackage from '../../utils/package_json';
 import Promise from 'bluebird';

src/ui/index.js

@@ -10,7 +10,7 @@ import UiExports from './ui_exports';
 import UiBundle from './ui_bundle';
 import UiBundleCollection from './ui_bundle_collection';
 import UiBundlerEnv from './ui_bundler_env';
-import i18nPlugin from '../plugins/i18n/server/i18n/index';
+import i18nPlugin from '../core_plugins/i18n/server/i18n/index';
 import langParser from 'accept-language-parser';
 
 let kibanaTranslations = [];