Fix limits when ES search isn't enabled globally

app/controllers/search_controller.rb

@@ -68,7 +68,7 @@ class SearchController < ApplicationController
   private
 
   def search_term_valid?
-    return true if Gitlab::CurrentSettings.elasticsearch_search?
+    return true if Gitlab::CurrentSettings.elasticsearch_search? && search_service.try(:use_elasticsearch?)
 
     chars_count = params[:search].length
     if chars_count > NON_ES_SEARCH_CHAR_LIMIT

spec/controllers/search_controller_spec.rb

@@ -116,21 +116,15 @@ describe SearchController do
           }
         end
 
-        where(:es_enabled, :string_name, :expectation) do
-          true  | :chars_under_limit | :not_to_set_flash
-          true  | :chars_over_limit  | :not_to_set_flash
-          true  | :terms_under_limit | :not_to_set_flash
-          true  | :terms_over_limit  | :not_to_set_flash
-          false | :chars_under_limit | :not_to_set_flash
-          false | :chars_over_limit  | :set_chars_flash
-          false | :terms_under_limit | :not_to_set_flash
-          false | :terms_over_limit  | :set_terms_flash
+        where(:string_name, :expectation) do
+          :chars_under_limit | :not_to_set_flash
+          :chars_over_limit  | :set_chars_flash
+          :terms_under_limit | :not_to_set_flash
+          :terms_over_limit  | :set_terms_flash
         end
 
         with_them do
           it do
-            allow(Gitlab::CurrentSettings).to receive(:elasticsearch_search?).and_return(es_enabled)
-
             get :show, params: { scope: 'projects', search: search_queries[string_name] }
 
             case expectation