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

tests/RTHydrationThenMPR.spec.ts

@@ -13,11 +13,15 @@ test('should hydrate an RTSTRUCT and then launch MPR', async ({ page }) => {
 
   await page.getByTestId('yes-hydrate-btn').click();
 
+  await page.waitForTimeout(5000);
+
   await checkForScreenshot(page, page, screenShotPaths.rtHydrationThenMPR.rtPostHydration);
 
   await page.getByTestId('Layout').click();
   await page.getByTestId('Axial Primary').click();
 
+  await page.waitForTimeout(5000);
+
   await checkForScreenshot(
     page,
     page,