Disable leak detector in unit evals

[bennetbo]

This does not provide value in the unit evals, and I see this panic sometimes when trying to run the unit evals

thread 'tools::evals::edit_file::eval_from_pixels_constructor' (14336149) panicked at crates/gpui/src/app/entity_map.rs:1116:9:
Exited with leaked handles:
Leaked handle for entity language::buffer::Buffer (EntityId(50v1)):

Release Notes:

• N/A

[bennetbo]

Closing in favour of #56029