Increase memory usage for Azure CI upgrade test

The test often fails when running in parallel to other tests as very
little memory is left. 389-ds memory autotuning causes database backend
to refuse working in such cases. 389-ds team suggested more memory has
to be made available.

Increate RAM for this test to 2.5GB instead of 2.2GB.

Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipatests/azure/azure_definitions/gating-fedora.yml

@@ -187,7 +187,7 @@ vms:
     containers:
       resources:
         server:
-          mem_limit: "2200m"
+          mem_limit: "2450m"
           memswap_limit: "3300m"
     tests:
     - test_integration/test_upgrade.py