Revert "perf: optimize test scheduling with --dist loadfile for 25% faster test runs (#157)"

This reverts commit 8879fcf.

The --dist loadfile optimization caused race conditions between tests that
share resources (e.g., test_custom_events_uuid and test_custom_events_list
both operate on custom events and can interfere with each other when run in
parallel by file).

Reliability > speed. Better to have tests take 40s with no race conditions
than 30s with intermittent failures.

Author: jeff-schnitter

Justfile

@@ -13,7 +13,7 @@ _setup:
 
 # Run all tests
 test-all: _setup test-import
-   {{pytest}} -n auto --dist loadfile -m "not setup" --html=report.html --self-contained-html --cov=cortexapps_cli --cov-append --cov-report term-missing tests
+   {{pytest}} -n auto -m "not setup" --html=report.html --self-contained-html --cov=cortexapps_cli --cov-append --cov-report term-missing tests
 
 # Run all tests serially - helpful to see if any tests seem to be hanging
 _test-all-individual:  test-import