tests: re-enable ltx tests using KILL command

LTX discovered a bug caused by not setting pid group while new EXEC
command are performed. This was causing *_stop tests to fail and it's
going to be fixed in the next release.

linux-test-project/ltx#2

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>

Author: acerv

libkirk/tests/test_ltx.py

@@ -301,18 +301,6 @@ class TestLTXSUT(_TestSUT):
     async def test_fetch_file_stop(self):
         pytest.skip(reason="LTX doesn't support stop for GET_FILE")
 
-    async def test_run_command_stop(self, sut):
-        if os.environ.get("GITHUB_ACTIONS"):
-            pytest.xfail("Unstable test under Github actions")
-
-        await super().test_run_command_stop(sut)
-
-    async def test_run_command_stop_parallel(self, sut):
-        if os.environ.get("GITHUB_ACTIONS"):
-            pytest.xfail("Unstable test under Github actions")
-
-        await super().test_run_command_stop_parallel(sut)
-
 
 class TestLTXSession(_TestSession):
     """