Tests: centralized test enabling logic, better parallelization in CI

Removing some heavy toolchains from windows/macos run (they will be tested only in the job based off the maximal docker image)

test/solidlsp/lean4/test_lean4_basic.py

@@ -16,6 +16,9 @@ import pytest
 
 from solidlsp.ls import SolidLanguageServer
 from solidlsp.ls_config import Language
+from test.conftest import language_tests_enabled
+
+pytestmark = pytest.mark.skipif(not language_tests_enabled(Language.LEAN4), reason="Lean4 tests are disabled (lean not available)")
 
 
 @pytest.mark.lean4