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

tests/RTNoHydrationThenMPR.spec.ts

@@ -11,10 +11,14 @@ test('should launch MPR with unhydrated RTSTRUCT', async ({ page }) => {
   await page.getByTestId('side-panel-header-right').click();
   await page.getByTestId('study-browser-thumbnail-no-image').dblclick();
 
+  await page.waitForTimeout(5000);
+
   await checkForScreenshot(page, page, screenShotPaths.rtNoHydrationThenMPR.rtNoHydrationPreMPR);
 
   await page.getByTestId('Layout').click();
   await page.getByTestId('MPR').click();
 
+  await page.waitForTimeout(5000);
+
   await checkForScreenshot(page, page, screenShotPaths.rtNoHydrationThenMPR.rtNoHydrationPostMPR);
 });