fix(segmentation overlays): Allow for the addition of multiple segmentation overlays. (#5189)

tests/RTDataOverlayNoHydrationThenMPR.spec.ts

@@ -19,6 +19,8 @@ test('should launch MPR with unhydrated RTSTRUCT chosen from the data overlay me
   // Hide the overlay menu.
   await page.getByTestId('dataOverlayMenu-default-btn').click();
 
+  await page.waitForTimeout(5000);
+
   await checkForScreenshot(
     page,
     page,
@@ -28,6 +30,8 @@ test('should launch MPR with unhydrated RTSTRUCT chosen from the data overlay me
   await page.getByTestId('Layout').click();
   await page.getByTestId('MPR').click();
 
+  await page.waitForTimeout(5000);
+
   await checkForScreenshot(
     page,
     page,