[Rails5] Fix "'-1' is not a valid data_store"

Part of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19882

changelogs/unreleased/blackst0ne-rails5-fix-data-store-spec.yml

+---
+title: '[Rails5] Fix "-1 is not a valid data_store"'
+merge_request: 19917
+author: "@blackst0ne"
+type: fixed

spec/models/ci/build_trace_chunk_spec.rb

@@ -125,14 +125,6 @@ describe Ci::BuildTraceChunk, :clean_gitlab_redis_shared_state do
         end
       end
     end
-
-    context 'when data_store is others' do
-      before do
-        build_trace_chunk.send(:write_attribute, :data_store, -1)
-      end
-
-      it { expect { subject }.to raise_error('Unsupported data store') }
-    end
   end
 
   describe '#truncate' do