fix: Integration test instability (#3597)

There are a couple of changes here which should improve stability of the tests.  Hopefully that will be sufficient, but it is difficult to tell for sure if it is complete.

extensions/measurement-tracking/src/viewports/TrackedCornerstoneViewport.tsx

@@ -259,8 +259,9 @@ function TrackedCornerstoneViewport(props) {
             patientAge: PatientAge || '',
             MRN: PatientID || '',
             thickness: SliceThickness
-              ? `${parseFloat(SliceThickness).toFixed(2)}mm`
+              ? `${parseFloat(SliceThickness).toFixed(2)}`
               : '',
+            thicknessUnits: 'mm',
             spacing:
               SpacingBetweenSlices !== undefined
                 ? `${parseFloat(SpacingBetweenSlices).toFixed(2)}mm`