`media::store::memory_store::tests::media_store_integration_tests_time::test_lease_locks` intermittently fails

https://github.com/matrix-org/matrix-rust-sdk/actions/runs/18275152000/job/52025455674

might just be a dumb "increase the timeout value" kind of solution, but I'd like to make sure it's that.

Also, there's an underlying question if the media store really needs the cross-process lock, because I don't think it needs it 🤔 