Move test that depends on ActiveRecord

This commit moves a test from `test/template` to `test/activerecord` since the
test depends on ActiveRecord.

This matches the documentation from [RUNNING_UNIT_TESTS](https://github.com/rails/rails/blob/f28d1ddd507174ac233b773cc4f35c3c05ad32e7/actionview/RUNNING_UNIT_TESTS.rdoc):

> Test cases in the test/activerecord/ directory depend on having activerecord and sqlite3 installed.
> If Active Record is not in actionview/../activerecord directory, or the sqlite3 rubygem is not installed, these tests are skipped.
> Other tests are runnable from a fresh copy of actionview without any configuration.

---

More details about this commit.

All the tests starting with `require 'active_record_unit'` are already
inside `test/activerecord`, except for the one test this commit moves.

If you don't have `active_record` on your machine, the following command
currently fails on master:

```bash
```
Merge pull request #17707 from claudiob/move-debug-helper-test

Move test that depends on ActiveRecord