Fixed bug which prevented historical images from loading. (#5271)

* Fixed bug which prevented historical images from loading.

imageLoadDelay variable would be initialized as a string when it's supposed to be initialized as an integer.

* Updated image load delay in E2E test.

* Implemented suggested tweak for parsing image delay.

Co-authored-by: John Hill <john.c.hill@nasa.gov>

e2e/tests/plugins/imagery/exampleImagery.e2e.spec.js

@@ -249,10 +249,8 @@ test('Example Imagery in Display layout', async ({ page }) => {
     await page.click('text=Example Imagery');
 
     // Clear and set Image load delay to minimum value
-    // FIXME: Update the value to 5000 ms when this bug is fixed.
-    // See: https://github.com/nasa/openmct/issues/5265
     await page.locator('input[type="number"]').fill('');
-    await page.locator('input[type="number"]').fill('0');
+    await page.locator('input[type="number"]').fill('5000');
 
     // Click text=OK
     await Promise.all([