Address ActiveRecord::InstrumentationTest#test_payload_connection_with_query_cache_enabled failure

This commit addresses `ActiveRecord::InstrumentationTest#test_payload_connection_with_query_cache_enabled` failure
with `postgresql` adapter because it executes `SHOW search_path` adds another notification that is executed via `sql_key`.
This statements is not executed by other database adapters.

- Failures fixed by this commit

```ruby
$ ARCONN=postgresql bin/test test/cases/instrumentation_test.rb -n test_payload_connection_with_query_cache_enabled
Using postgresql
Run options: -n test_payload_connection_with_query_cache_enabled --seed 65179

F

Failure:
ActiveRecord::InstrumentationTest#test_payload_connection_with_query_cache_enabled [test/cases/instrumentation_test.rb:142]:
Expected 2 instead of 3 notifications for sql.active_record.
Expected: 2
  Actual: 3

bin/test test/cases/instrumentation_test.rb:138

Finished in 0.029114s, 34.3482 runs/s, 34.3482 assertions/s.
1 runs, 1 assertions, 1 failures, 0 errors, 0 skips
$
```

Fix rails#53858
Related to rails#53822

Author: yahonda

activerecord/test/cases/instrumentation_test.rb

@@ -138,15 +138,16 @@ def test_payload_connection_with_query_cache_disabled
     def test_payload_connection_with_query_cache_enabled
       connection = ClothingItem.lease_connection
 
-      payloads = capture_notifications("sql.active_record") do
-        assert_notifications_count("sql.active_record", 2) do
-          Book.cache do
-            Book.first
-            Book.first
-          end
+      notifications = capture_notifications("sql.active_record") do
+        Book.cache do
+          Book.first
+          Book.first
         end
-      end.map(&:payload)
+      end
+
+      payloads = notifications.select { _1.payload[:sql].match?("SELECT") }.map(&:payload)
 
+      assert_equal 2, payloads.size
       assert_equal connection, payloads.first[:connection]
       assert_equal connection, payloads.second[:connection]
     end