Fix tag name in testing_file.json from el8->el10

Signed-off-by: Petr "Stone" Hracek <[email protected]>

Author: phracek

tests/imagestreams/testing_file.json

@@ -46,7 +46,7 @@
         "referencePolicy": {
           "type": "Local"
         },
-        "name": "2.4-el8"
+        "name": "2.4-el10"
       }
     ]
   }