Merge branch 'jc-feature-flag-find-all-tags' into 'master'

Add feature flag for FindAllTags

See merge request gitlab-org/gitlab-ce!25615

lib/gitlab/gitaly_client.rb

@@ -228,7 +228,7 @@ module Gitlab
       result
     end
 
-    SERVER_FEATURE_FLAGS = %w[].freeze
+    SERVER_FEATURE_FLAGS = %w[go-find-all-tags].freeze
 
     def self.server_feature_flags
       SERVER_FEATURE_FLAGS.map do |f|
@@ -244,7 +244,9 @@ module Gitlab
     end
 
     def self.feature_enabled?(feature_name)
-      Feature.enabled?("gitaly_#{feature_name}")
+      Feature::FlipperFeature.table_exists? && Feature.enabled?("gitaly_#{feature_name}")
+    rescue ActiveRecord::NoDatabaseError
+      false
     end
 
     # Ensures that Gitaly is not being abuse through n+1 misuse etc