ctest: Disable label time summary after running tests

It's mostly redundant, as ctest already prints timing information
for each individual test:

 1/1 Test #572: tst_qwindowcontainer .............   Passed    0.71 sec

And we track test timing though the JUnit and Qt XML files we produce
and ship to our Grafana dashboard.

Change-Id: I374d0b2201efabccec18da6358e3859b02702c27
Reviewed-by: Dimitrios Apostolou <jimis@qt.io>
Reviewed-by:  Alexey Edelev <alexey.edelev@qt.io>

coin/instructions/cmake_run_ctest.yaml

@@ -88,6 +88,10 @@ instructions:
       property: features
       contains_value: AbortTestingOnFirstFailure
 
+  - type: AppendToEnvironmentVariable
+    variableName: CTEST_ARGS
+    variableValue: " --no-label-summary"
+
     # Enable CTest's JUnit XML summary
   - type: AppendToEnvironmentVariable
     variableName: CTEST_ARGS