Use Rails upsert to generate update_count! query in Counters concern (#28738)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

spec/models/concerns/account/counters_spec.rb

@@ -44,5 +44,18 @@ describe Account::Counters do
 
       expect(account.statuses_count).to eq 5
     end
+
+    it 'preserves last_status_at when decrementing statuses_count' do
+      account_stat = Fabricate(
+        :account_stat,
+        account: account,
+        last_status_at: 3.days.ago,
+        statuses_count: 10
+      )
+
+      expect { account.decrement_count!(:statuses_count) }
+        .to change(account_stat.reload, :statuses_count).by(-1)
+        .and not_change(account_stat.reload, :last_status_at)
+    end
   end
 end