fix new test description

Author: xfalcox

spec/jobs/scheduled/embeddings_backfill_spec.rb

@@ -69,7 +69,7 @@
     expect(index_date).to be_within_one_second_of(Time.zone.now)
   end
 
-  it "backfills topics based on bumped_at date" do
+  it "backfills embeddings for the ai_embeddings_backfill_model" do
     SiteSetting.ai_embeddings_backfill_model = vector_def2.id
     SiteSetting.ai_embeddings_backfill_batch_size = 100