test: increase wait time in ProperCopy to avoid flakiness (#36)

Author: hazzik

src/NHibernate.Search.Tests/Async/DirectoryProvider/FSSlaveAndMasterDPTest.cs

@@ -60,7 +60,7 @@ public async Task ProperCopyAsync()
             await (tx.CommitAsync());
             session.Close();
 
-            int waitPeriodMilli = 2 * 1 * 1000 + 10; //wait a bit more than 2 refresh (one master / one slave)
+            var waitPeriodMilli = TimeSpan.FromSeconds(1.5 * 2); //wait a bit more than 2 refresh (one master / one slave)
             await (Task.Delay(waitPeriodMilli));
 
             // assert that the master has indexed the snowstorm

src/NHibernate.Search.Tests/DirectoryProvider/FSSlaveAndMasterDPTest.cs

@@ -49,7 +49,7 @@ public void ProperCopy()
             tx.Commit();
             session.Close();
 
-            int waitPeriodMilli = 2 * 1 * 1000 + 10; //wait a bit more than 2 refresh (one master / one slave)
+            var waitPeriodMilli = TimeSpan.FromSeconds(1.5 * 2); //wait a bit more than 2 refresh (one master / one slave)
             Thread.Sleep(waitPeriodMilli);
 
             // assert that the master has indexed the snowstorm