Don't bundle Development Test on macOS

[rollerozxa]

This PR removes devtest from the macOS app bundle.

When devtest was originally no longer installed it caused macOS unit tests to fail, as the unit tests required devtest to be present and macOS needs the engine to be installed first to run the unit tests. So it was enabled there in CI to make the problem go away. This unfortunately made it be still be bundled with the engine on macOS as the CI artifacts are used as releases, which has probably caused some confusion for 5.8 when MTG was debundled.

This PR does, what I probably should have done originally, and disable installing devtest again between when the engine is installed for unit tests and an app bundle is packaged.

To do

This PR is a Ready for Review.

How to test

Check the resulting CI artifact in this PR, compare to the 5.8.0 one and see that devtest is no longer present.

[sfan5]

as the unit tests required devtest to be present and macOS needs the engine to be installed first to run the unit tests

Was this actually a thing or was it only that you needed the bundle file structure to run anything graphical?

[rollerozxa]

Was this actually a thing or was it only that you needed the bundle file structure to run anything graphical?

I don't think it should be necessary to install it to run the unit tests, but the path code is so hairy I don't know for sure. Running a compiled RUN_IN_PLACE=0 Minetest binary on macOS when moved from bin/ to ./ relative to the source tree makes it correctly find the source tree's engine data in my VM (it does not when kept in bin/).