Make searching saved objects more powerful with query_string (#9870)

* switch to query_string query

and only append trailing * when the query is a simple word

* swallow 400 errors from query_string query

attempt to mimic simple_query_string...

> Unlike the regular query_string query, the simple_query_string query will never throw an exception, and discards invalid parts of the query
> https://www.elastic.co/guide/en/elasticsearch/reference/5.1/query-dsl-simple-query-string-query.html

* simplify the regexp

no grouping required, and matching 1 or more is fine, as this condition isn't met when the searchString is empty

src/core_plugins/kibana/public/management/sections/objects/_objects.js

@@ -37,6 +37,7 @@ uiModules.get('apps/management')
       const getData = function (filter) {
         const services = registry.all().map(function (obj) {
           const service = $injector.get(obj.service);
+
           return service.find(filter).then(function (data) {
             return {
               service: service,

src/ui/public/courier/saved_object/saved_object_loader.js

@@ -78,11 +78,12 @@ export class SavedObjectLoader {
    */
   find(searchString, size = 100) {
     let body;
+
     if (searchString) {
       body = {
         query: {
-          simple_query_string: {
-            query: searchString + '*',
+          query_string: {
+            query: /^\w+$/.test(searchString) ? `${searchString}*` : searchString,
             fields: ['title^3', 'description'],
             default_operator: 'AND'
           }
@@ -98,6 +99,19 @@ export class SavedObjectLoader {
       body,
       size
     })
+      .catch(err => {
+        // attempt to mimic simple_query_string, swallow formatting error
+        if (err.statusCode === 400) {
+          return {
+            hits: {
+              total: 0,
+              hits: [],
+            }
+          };
+        }
+
+        throw err;
+      })
       .then((resp) => {
         return {
           total: resp.hits.total,