Moving pytests to model-config-tests

[jo-basevi]

As part of this issue: https://github.com/ACCESS-NRI/model-config-tests/issue/1, the test folder is being moved to a separate model-configs-tests repository.

The test folder in the main branch will be able to be removed, and CI updated to use the new repository for test code.

Currently reproducibility test run on gadi uses vars.REPRO_TEST_LOCATION :
https://github.com/ACCESS-NRI/reproducibility/blob/5c3ca6f1fa9c85e5fe6f34e77bcc844a16e13c10/.github/workflows/checks.yml#L64
So I think the changes there would require changing the repository at vars.REPRO_TEST_LOCATION to model-config-tests

[jo-basevi]

Closed by #104 and REPRO_TEST_LOCATION were updated to point to model-config-tests repository