Check exact array contents instead of inclusion

We're using `eq` and `match_array` in most places, but there were a few
places where we were still checking each element is included in the
array. This is a bit dangerous, because the array could have duplicate
elements, and we wouldn't detect them with `include`.

spec/models/local_census_record_spec.rb

@@ -59,7 +59,7 @@ describe LocalCensusRecord do
 
     context "search" do
       it "filter document_numbers by given terms" do
-        expect(LocalCensusRecord.search("A")).to include a_local_census_record
+        expect(LocalCensusRecord.search("A")).to eq [a_local_census_record]
         expect(LocalCensusRecord.search("A")).not_to include b_local_census_record
       end