[ci] Build Ubuntu 25 in release mode

to make the execution of tests faster

Author: dpiparo

.github/workflows/root-ci.yml

@@ -371,7 +371,7 @@ jobs:
           - image: ubuntu2404
             overrides: ["CMAKE_BUILD_TYPE=Debug"]
           - image: ubuntu2504
-            overrides: ["CMAKE_BUILD_TYPE=Debug", "CMAKE_CXX_STANDARD=23"]
+            overrides: ["CMAKE_CXX_STANDARD=23"]
           - image: debian125
             overrides: ["CMAKE_CXX_STANDARD=20", "dev=ON"]
           # Special builds