Use JDK 24.0.2 (EA) for testing the 24.2 dev tree

The April release will be 24.2.2 corresponding to the JDK 24.0.2 update
and we should test with that JDK to be prepared for breakage caused by
the JDK update.

Author: jerboaa

.github/workflows/mandrel.yml

@@ -35,7 +35,7 @@ jobs:
       repo: ${{ github.repository }}
       version: ${{ github.ref }}
       mandrel-packaging-version: "24.2"
-      jdk: "24/ga"
+      jdk: "24/ea"
   q-main-ea-win:
     name: "Q main M 24.2 windows EA"
     uses: ./.github/workflows/base-windows.yml
@@ -44,4 +44,4 @@ jobs:
       repo: ${{ github.repository }}
       version: ${{ github.ref }}
       mandrel-packaging-version: "24.2"
-      jdk: "24/ga"
+      jdk: "24/ea"