Remove body_as_json in favor of built-in response.parsed_body for JSON response specs (#31749)

spec/requests/api/v1/suggestions_spec.rb

@@ -32,7 +32,7 @@ RSpec.describe 'Suggestions' do
     it 'returns accounts' do
       subject
 
-      expect(body_as_json)
+      expect(response.parsed_body)
         .to contain_exactly(include(id: bob.id.to_s), include(id: jeff.id.to_s))
     end
 
@@ -42,7 +42,7 @@ RSpec.describe 'Suggestions' do
       it 'returns only the requested number of accounts' do
         subject
 
-        expect(body_as_json.size).to eq 1
+        expect(response.parsed_body.size).to eq 1
       end
     end