[releases/1.2] Fix the discovery service to not terminate on parent process closure (#391)

* Add DETACHED_PROCESS flag to detach the discovery process from its parent console process

* Fix test failure

---------

Co-authored-by: Joel Dixon <38357562+dixonjoel@users.noreply.github.com>

Author: samchris007

ni_measurementlink_service/_internal/discovery_client.py

@@ -268,7 +268,7 @@ def _start_service(
     kwargs: Dict[str, Any] = {}
     if sys.platform == "win32":
         # Terminating the measurement service should not terminate the discovery service.
-        kwargs["creationflags"] = subprocess.CREATE_BREAKAWAY_FROM_JOB
+        kwargs["creationflags"] = subprocess.CREATE_BREAKAWAY_FROM_JOB | subprocess.DETACHED_PROCESS
     discovery_service_subprocess = subprocess.Popen(
         [exe_file_path],
         cwd=exe_file_path.parent,

tests/unit/test_discovery_client.py

@@ -193,7 +193,7 @@ def test___discovery_service_exe_unavailable___register_service___raises_file_no
 def subprocess_popen_kwargs() -> Dict[str, Any]:
     kwargs: Dict[str, Any] = {}
     if sys.platform == "win32":
-        kwargs["creationflags"] = subprocess.CREATE_BREAKAWAY_FROM_JOB
+        kwargs["creationflags"] = subprocess.CREATE_BREAKAWAY_FROM_JOB | subprocess.DETACHED_PROCESS
     return kwargs