Fix flaky BoundaryTimerEventTest by fixing the clock before process start

The timer due date was computed from the real system clock, but the
clock was only advanced relative to a Date captured before the process
started. On slow databases the elapsed time between capturing startTime
and the actual timer creation could exceed the 5-second buffer, leaving
the timer not yet executable when the wait loop checked.

Author: filiphr

modules/flowable-engine/src/test/java/org/flowable/engine/test/bpmn/event/timer/BoundaryTimerEventTest.java

@@ -78,6 +78,7 @@ public void testMultipleTimersOnUserTask() {
 
         // Set the clock fixed
         Date startTime = new Date();
+        processEngineConfiguration.getClock().setCurrentTime(startTime);
 
         // After process start, there should be 3 timers created
         ProcessInstance pi = runtimeService.startProcessInstanceByKey("multipleTimersOnUserTask");
@@ -174,6 +175,7 @@ public void testTimerOnAsyncMultiInstanceActivity() {
     public void testExpressionOnTimer() {
         // Set the clock fixed
         Date startTime = new Date();
+        processEngineConfiguration.getClock().setCurrentTime(startTime);
 
         HashMap<String, Object> variables = new HashMap<>();
         variables.put("duration", "PT1H");
@@ -208,6 +210,7 @@ public void testExpressionOnTimer() {
     public void testExpressionWithJavaDurationOnTimer() {
         // Set the clock fixed
         Date startTime = new Date();
+        processEngineConfiguration.getClock().setCurrentTime(startTime);
 
         HashMap<String, Object> variables = new HashMap<>();
         variables.put("duration", Duration.ofHours(1));