Fix timing issue in ctrl_mpexec unit test (DM-26974)

EXpect timeouts also for tasks that are supposed to finish successfully.
Adjusted timings to make this situation less frequent.

tests/test_executors.py

@@ -29,6 +29,7 @@
 import time
 from types import SimpleNamespace
 import unittest
+import warnings
 
 from lsst.ctrl.mpexec import MPGraphExecutor, MPGraphExecutorError, MPTimeoutError, QuantumExecutor
 from lsst.ctrl.mpexec.execFixupDataId import ExecFixupDataId
@@ -141,7 +142,7 @@ class TaskMockSleep:
 
     def runQuantum(self):
         _LOG.debug("TaskMockSleep.runQuantum")
-        time.sleep(3.)
+        time.sleep(5.)
 
 
 class TaskMockNoMP:
@@ -251,10 +252,16 @@ def test_mpexec_timeout(self):
 
         # with failFast=False exception happens after last task finishes
         qexec = QuantumExecutorMock(mp=True)
-        mpexec = MPGraphExecutor(numProc=3, timeout=1, quantumExecutor=qexec, failFast=False)
+        mpexec = MPGraphExecutor(numProc=3, timeout=3, quantumExecutor=qexec, failFast=False)
         with self.assertRaises(MPTimeoutError):
             mpexec.execute(qgraph, butler=None)
-        self.assertCountEqual(qexec.getDataIds("detector"), [0, 2])
+        # We expect two tasks (0 and 2) to finish successfully and one task to
+        # timeout. Unfortunately on busy CPU there is no guarantee that tasks
+        # finish on time, so expect more timeouts and issue a warning.
+        detectorIds = set(qexec.getDataIds("detector"))
+        self.assertLess(len(detectorIds), 3)
+        if detectorIds != {0, 2}:
+            warnings.warn(f"Possibly timed out tasks, expected [0, 2], received {detectorIds}")
 
     def test_mpexec_failure(self):
         """Failure in one task should not stop other tasks"""