Chore: Ensure we save correct default admin user in integration test DB setup (#105752)

* fix helper + amend tests

* fix import + remove unused var

* remove more users

* remove unused code

* update test comment

pkg/tests/api/plugins/api_plugins_test.go

@@ -31,7 +31,7 @@ import (
 )
 
 const (
-	usernameAdmin    = "admin"
+	usernameAdmin    = "otherAdmin"
 	usernameNonAdmin = "nonAdmin"
 	defaultPassword  = "password"
 )